I see. Then I should let you know that overclocking parts dont perform any better than non-overclocking parts, unless you are overclocking.
For example, your motherboard is great for overclocking. And your RAM is overclockable.
If you replaced those parts with ones that arent great for overclocking, but are still awesome for normal (non-overclocking) use, you wont notice any difference in performance, but will notice your wallet not being so light
For RAM, I recommend the CORSAIR ValueSelect 1GB (2 x 512MB) 184-Pin DDR SDRAM Dual Channel Kit System Memory - Retail
Like I said, it wont overclock that great, but it wont perform and differently than fancy overclocking RAM.
As for a motherboard, the GIGABYTE GA-K8N Ultra-9 Socket 939 NVIDIA nForce4 Ultra ATX AMD Motherboard - Retail
or the MSI K8N Neo4 Platinum Socket 939 NVIDIA nForce4 Ultra ATX AMD Motherboard - Retail
would be good. And again, these boards arent the best overclockers (the DFI is), but will perform no worse than the DFI when not overclocking. These boards are also stable and reliable.