That looks beefy enough and a good price.
You mentioned you have other hard drives.
If you have a spare install it in your new computer as a slave and go into your cmos and alter the boot sequence to boot from that drive. On that one install XP as a fail safe incase Vista wigs out on you. Install all your stuff like you were going to. Then go back and change the boot sequence to the original and run Vista as long as you want.
If you have no problems then you never need to go to the other drive. But if you do as long as you set up Sonar to keep the files in the same spot regardless of what drive it's on. Because you can still have acces to either drive no matter what you boot off of.
If that is too confusing save you current files that you are working on as Bundle files and you won't have to worry about where they are.
I know that's probably too much information. But it sounds a lot harder than it is.