You can get a Venice up to 2.7 with no problem if your motherboard is good. I'd recommend DFI or ABIT for the mobo. You might get some serious bottlenecks if you try to OC with that memory you have. If you have some spare money might want to look into the new OCZ, the TDD5 Chips are looking very nice. Also would recommend getting a better heatsink/fan as well, if you go OEM you wont be spending that much more. Also I'm quite partial to the ATI X700 but thats just me.
Also remember just because the CPU has a low frequency doesnt mean it isnt fast, look at the cache on that venice.
G/L with the build.