This is a "VEGAS" forum, not an AMD forum. If you need reviews of hardware and how it performs on different applications, then goto Tomshardware.com, you will have much better success there. No one here owns every system to be able to give you a which is better kind of answer. We can only give you what we already have experience with. Tom's hardware does an apples to apples comparison of similar hardware, it may not actually use Vegas to do it's testing but it does use similar applications.
These are the forums where the real hard-core AMD guys hang out. They have never failed to answer one of my (many) AMD motherboard-related questions.
A dual XP machine should run VV3 wonderfully. Check the review at the top of this message board for their take...one of their test machines was a dual XP 1800+ (can't remember the MB)
Athon's Dual is an MP, not an XP. I'm getting the Tiger MP. It does not come with LAN or SCSI. Go to www.monarchcomputer.com. Call and ask to speak to Michael. He knows the Athlons and is very helpful.