I agree with Bombdig, if you are spending that much cash for hardware, the cost of a CS5 upgrade should be trivial, especially considering half that hardware is useless with CS4. I also agree with at least part of what Fish said, Vegas really is not for pros. People pretend, they certainly try hard, but it is not a professional product. I can use just about any software and platform I want, and I use CS5 on Win7. (I just wish they'd cross it to Linux)
I also recommend dumping the raid0 for raid 5, But raid 0 is better than Raid 1, but you MUST back up early and often... (Just like voting.)
And to answer your basic question, Yes, it should do fine.