If you want more games, go for PS3. If you want better graphics, then you should go for the GPU.
The way I see it, you may as well get the PS3 because it just had a price drop. There might be a price cut on the GPU by the time you save up for that as well. Its not like your GPU failed or something, you can still play the PC games.
edit: Ok so your brother's problem...then maybe you should get a new GPU. Depends upon how much it would help him. If there was no other way for your brother than yeah you can solve 2 problems with GPU whereas the PS3 will just be sitting there with no games.







