Sell your current motherboard + Processor + RAM + Graphics card for around (estimated)
600 + 600 + 800 + 1200 = 3200/-
I'd provide the following suggestion an the expense of bwing flamed by teh intel fanbois (i aint an amd fanboi)
AMD Athlon X2 - 6000+ ==> ~4K
690G ==> 2.5k
Corsair Vlaue Select 2x1 GB DDR2 ==> 1.8K
=8300/-
so 1700 + 3200 = 3900/- this can fetch you a 8600GT.
Alternatively you can also consider
any G31 board ==> 2.5K
E2180 = 3.5K
Corsair Vlaue Select 2x1 GB DDR2 ==> 1.8K
= 7800
3200 + 2200 = 5400/- you can get a 9600gso at this cost