What type of memory card is it, what make, where did you get it from and has it got any files on already? (had to ask...) There are snide memory cards out there....

Incidentally, I purchased a Sony memory stick from Play.com quite a while ago, and whilst the packaging said 2GB, the actual card was only 1GB - luckily it was in their clear plastic carton thing and I noticed before I opened it. Packaging didn't look like it was tampered with either.