Nokia 6600

no, you cannot use the Sd card. I tried one and it would not physically fit. The SD card is slightly thicher if I recall. I bought a 256MB MMC card and it works great.

I don't think I'll even fill up half that card and I have dozens of wall papers and mp3 ring tones.

Nope, it's a different size. Has to be MMC. They aren't that expensive, but they can be hard to find (and most ads in the paper won't mention them since they aren't as popular a format).