That will be better to have as less "main setup pack" as possible.
So I would go the most powerfull ones.
LGA 775 Mobo+CPU+ DDR2 RAM are quite cheap. You dont have to use SSD either.
Ok it is much faster but a very cheap HDD will work as well for the rig.
I dont say these are negligible costs but they base cost can be very minimal.
I also prefer powerful gpu as well though. Fewer cards. Easier to manage.