A hard drive?
I don't think 64GB is anywhere near enough to be your total system storage...after you load a few games you'll be out of room and that's before adding your music/video/downloads/etc. If you're going to go with an SSD (personally I think they're unnecessary and overpriced but w/e, if you desperately need loading times that fast go for it) then you'll most likely want a second regular HDD to keep your large stuff on.
I have a separate server PC that keeps all my movies/music/backups of software/etc, but even just installing games, game addons, and programs my desktop's 640GB WD Caviar Black SATAIII drive has 137GB used. If you choose to go with just a tiny SSD you'll find yourself having to uninstall and reinstall games constantly which could be painful depending on how many new games you play.
