which setup is better?//

#1 :

ASRock ALIVENF6G-VSTA AM2 NVIDIA GeForce 6100 or 6150SE / nForce 430 (Depend on the version) Micro ATX AMD Motherboard - Retail

PNY VCG7900SXPB GeForce 7900GS 256MB 256-bit GDDR3 PCI Express x16 SLI Supported Video Card - Retail

AMD Athlon 64 X2 4200+ Brisbane 2.2GHz Socket AM2 65W Processor Model ADO4200DDBOX - Retail

A-DATA Value Series 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 667 (PC2 5300) Dual Channel Kit Desktop Memory Model VDQPE1A16K - Retail

OR #2:

GIGABYTE GA-MA69GM-S2H AM2 AMD 690G HDMI Micro ATX AMD Motherboard - Retail

PNY VCG86512GXPB-OC GeForce 8600GT 512MB 128-bit GDDR3 PCI Express x16 HDCP Ready SLI Supported Video Card - Retail

AMD Athlon 64 3800+ Orleans 2.4GHz Socket AM2 Processor Model ADA3800CWBOX - Retail

OCZ Value Series 1GB 240-Pin DDR2 SDRAM DDR2 667 (PC2 5400) Desktop Memory Model OCZ26671024V - Retail x2

which setup is better?

Obviously choice no.1.

The 7900GS and the X2 4200+ is already a no-brainer pwning the 3800+ and 8600GT.