Thanks everyone for your help!

My final setup, which I've already ordered:

Motherbord: MSI K8N Diamond plus
Processor: AMD Athlon 64-x2 4200+ dual core with original cooler (can always get another one if this one isn't good enough).
Memory: 2x PQI 1024 MB DDR400
Videocard: MSI PCI-E NX7800 GT-VT2D256E
Harddisk: Hitachi S-ATA II 300 MBs 8 Mb 250GB
DVD Player + RW: Benq
Audio: Sound 7.1 onboard