As others have already mentioned, it's really about assessing your needs. If you plan to use the PS3 as an all in one type media center, then a hard drive upgrade may be necessary. No matter what though, I do not recommend buying the 250 GB version. For less than $150 you could upgrade that drive to a decent 500 to 640 GB drive.

I bought the 40 GB version back in 2008 and promptly upgraded to 250 GB since I planned on downloading videos as well as some PS1 classics. With games and videos installed, I've used a good 70 GB or so. Not to mention, even with the 250 GB drive, only around 200 GB is usable.