[ElfBane]

I am a computer tech, both in the Navy (AT1 USN-Ret) and also do CP repair in retired life(A+ certified). The WD brand is reliable and is a good value. I would get the 250GB and partition it thusly, 80, 80, 80. I like to keep the OS on the primary, and as much as possible on the other partitions. I do it this way so my backups will be manageable and not take forever. I backup the primary with Ghost once a month, and the other partitions about every 2 months.
Also in my experience, Seagate is a good value. HOWEVER, they did buy Maxtor, one of the most unreliable HDD manufacturers, IMO. Seagate didn't merge the Maxtor brand in with the Seagate brand, they kept it separate. So Seagate may be worth a look.
Anyway, HDD space it pretty cheap right now, so go ahead and get a 250GB in case you need it in the future. ALSO, the solid state HDD's are coming out..you may want to try one of those..but they aren't cheap!
Hope this helps