<<snipped original message> >

Memory is not my issue - have plenty of memory cards around here.  Yes, I
found something that worked for my specific purpose of posting a picture to
ebay (and my item sold right away - an added bonus of that nice picture).
Is my little solution the answer to all of my hopes & dreams for my dig
photo taking? Nope.

At first I was a bit insulted by your post - who is Martin to claim I don't
have an understanding of basic mathematics?  He has no idea that my job
requires me to perform advanced calculations on my fancy calculator all day
long!  : )   However, before getting all defensive I re-read your post and
decided, that hey, you're right - I haven't bothered to learn the basics of
photography.  Call me lazy - I was looking for a quick answer.  Yes yes, I
understand that the higher the number of pixels, the clearer the image.
Monet and pointillism are not lost on me.  Yes yes, I know there is math
involved.   Feel free to point me to a good resource to read up a bit more
about digital photography & photo-editing, and rest assured I will learn all
the necessary math!

-stars
(a "she")

Stars,

If I'm reading your original questions correctly, (and quite possibly I'm
not), here's what I do with my 5 megapixel digital for printing and
displaying on a monitor or web site. I always shoot my pics with the
intention of getting the best quality I can for prints up to 8x10, but
knowing I most likely will make 4x6 prints, and will want to post pics on
the web or use the pics for monitor wallpaper or to email for someone to
view on a monitor. This may be more info than you could possibly need.

I always take the pics with the largest capture size and least compression
done inside the camera itself. In your case, I think maybe that's the Large
setting and whichever the compression setting is for the least amount of
compression (either SuperFine or Normal... check the manual). This will give
you the most information/data for every pic. You can throw away some of this
data during the editing, but you can never "add" quality/data back in to
enlarge a small pic to make it a larger one.

When I transfer my pics from the memory card to my PC, I save two copies of
each pic; one copy to a folder I call "archive" and the second copy to
another folder I name corresponding to the event where the pics were taken.
I never again touch the copies in the "archive" folder. That's a safety net
folder in case I edit something horribly wrong, I can recover the original.
I always edit the pics in the second folder.

I use PhotoShop Elements for my editing program, but I'm sure you can do
this same set of procedures with whatever editing program came with your
digital camera.

I'm going to make a 4x6 print: I open the pic from the second folder with my
editing program, I choose "resize", and unclick the "resample" box; if the
pic is landscape-oriented, I choose resize the width to 6" (and the height
will be resized to 4.5"); if it's a portrait-oriented pic, set the height to
6", (and the width will be resized to 4.5"). Next, crop your pic to get that
extra 1/2" of material out of the 4.5" dimension so it'll fit onto 4x6"
print paper without the printer driver randomly cropping the pic. Once
you've done that, then go back to the "resize" menu, checkmark the
"resample" box, and then enter "300" into the dots per inch field. Now, save
this edited pic as something other than the original you started out with.
(Maybe add a number or letter to the original name when you're saving it).
More importantly, you might also want to change the file "type" from a "jpg"
file to "tiff" or "psd" format file when you save it. ("jpg" format files
are already compressed files, and every time you "save" a jpg file, you
throw away/lose clarity/detail information when the jpg compression is done
again to save the file. "jpg" format is a "lossy" format. The "tiff" and
"psd" formats are "loss-less" formats). Most all photo printers for us
consumers eat 300 dots per inch as their most efficient input. You can feed
your printer more than that, but I've found it makes no difference at all to
the quality of the print, and sometimes the extra dots per inch choke the
printer or at least slow it down. Now, you'll have terrifically clear 4x6
prints of whatever your digital camera saw. If you're going to send the
edited pics to ofoto.com or another site to have prints made, you also need
to save the final edited file in "jpg" format because I think that's the
format they want you to send to them.

Once you've done the above, and you decide you want to display the 4x6 pics
(you already edited for printing) on a monitor, go back into your editing
program to "resize", make sure the "resample" box is checked, and then put
"72" in the dots per inch window and click okay. This will have several
effects: it'll give you a significantly smaller file saved on your PC's hard
drive, it'll be a smaller file to email, and it'll be the optimum dots per
inch for displaying a 4x6" picture on a monitor or on a web site. Save this
file as yet another modified name from the (edited 4x6 print) input file. If
you're going to send it to someone to display on a monitor, save it also as
a "jpg" format file to send out, (since "jpg" is a pretty universal format
file that both Mac and PC users can display on a monitor).

Okay. Told you this was going to be more info than you needed. One last
pointer: Be sure to back up your hard drive onto floppies, CDs, DVDs, or
another hard drive in (or outside of) your PC, so in case your hard drive
hiccups, you won't have lost all your originals and your time-consuming
edited pics. Enjoy!

 ...Karl