Switching from DPS Velocity to FCP 7, advice on building the most efficient system??

Switching from DPS Velocity to FCP7, advice on building most efficient MacPro system?

Hi, new to forum & serious video editing on the mac. Am looking for advice I have a PC switcher, who up till now has been using DPS Velocity & has decided to switch over the Mac. The idea is to get Mac Pro 8 core (2.26/2.66/2.93??), run Final Cut Pro 7, and load 8GB of memory.
Would I need to go for a Raid array of internal disks, can anyone give me quick Raid for dummies how & why to use?
Or am i okay with 2 TB Hard Drives?
Or do I get the 2TB Hard Drives that i run on Raid, am a bit confused.

Also how do these video editing systems compare?
Given that DPS Velocity is probably 2 versions older than current version.

Thanks in advance for all feedbacks.

Well FCP is a pretty big application, The more power the better I would say,

Raid is very easy on a mac- Get all the drives you want then boot off you install disk and in about 3 steps have them raided.

I have bo idea about the velocity question, but FCP is very nice