I have a Nokia 6230, I bought it a few years ago so I only have a couple of 256MMC cards for it.
Looking at getting a SLVR, what do you think about yours?? My 6230 is pretty cool, except that it crashes every now and then, (gotta love first gen technology eh??)
Anyway, I'd be weary of any non namebrand stuff, unless you can find definite proof that it either really is the same thing as the namebrand company, (and under a different name) which the majority of the "unknown" name stuff seems to be, or is just too good of a deal that if it is junk, it's not too big of a loss for you. Good luck!
