You people saying that SSDs are unnecessary have obviously never used one! An SSD is probably the best performance improvement you can make to any computer, well worth the money IMO. I've got 2 x 30GB SSDs, which didn't cost a massive amount, in RAID 0. Obviously not enough for everything - I have a normal hard drive for documents, and programs which I don't run, but it's enough for Windows 7 + WOW and makes a massive difference.
The thing I used to use to compare was flying into Dalaran - before I put an SSD in, the whole system would slow down as it loaded (presumably) the models for each player. Now all of that is gone - characters still appear slowly, but it no longer makes the motion on the screen stop.
If you can afford it, get yourself an SSD! You won't regret it, and costs have fallen significantly (though yes, they are still a lot more than hard drives).
