I think it largely depends on how you are going to use Vegas. If you are just editing dv, my old Pentium 3 1GHZ worked fine, so just about any new Pentium 4 or AMD processor would work for you. If you are working with HDV and using say Magic Bullet Movie Looks HD, buy the best you can afford. Oops, let me back up, there is Gear Shift available at the VASST web site that enables you to work with dv proxies and then render back to HDV, so you can work with HDV with a much slower processor. I have an AMD X2 dual core 4400 and I watch my frame drop substantially when I apply MB Movie Looks which makes me wish I had bought the fastest AMD dual core instead of the one I got.
I would definitely recommend getting at least 2 hard drives and use one just for your video files. I think 2 GB of RAM is kind of the norm for most of us, though some have 4 or more. You want a fire wire card obviously so you can capture vid from your cam. If you can afford 2 monitors, that would be great too. You will need a video card that has 2 dvi outs (assuming you're not using crt monitors) and supports your monitors native res. I have 2 of the 24" Dell LCD's. They cost around $800 or so each during one of the frequent sales/specials they have.
The last thing you'll have to decide is whether or not to go with Dell, HP, etc. or to go with a custom builder (assuming you are not capable of building your own box). The cool thing about a custom built pc from Boxx Tech, Falcon NW, VooDoo, etc. or a smaller company/builder is that you won't have a bunch of software installed on your machine that you don't need or want which can slow your computer down. I recall DSE posting months ago something about a builder that can make you a dual core AMD machine for less than $2,500. Do a search on his name DSE and "builder" and it should come up.
Ideally you would have a computer that's used just for editing and not have anything else installed on it that you don't need for that purpose. This is something I plan on doing later in the year. I'm sure someone else will mention anything else that I may have left out. I’ll paste my system details below. Derek
System:
XP Pro SP2 (with all updates)
Asus A8N-SLI MB
Athlon 64 4400+ Dual Core
Zalman CNPS700BLED CPU COOLER
2GB 400mhz PC3200 DDR
GEFORCE 7800 GT
WD 250GB SATA (SYSTEM DRIVE)
MAXTOR DIAMONDMAX 10 300GB SATA (16MBC)
DUAL DVD DRIVES
LOGITECH DINOVO MEDIA DESKTOP (Bluetooth KB/MOUSE)
SIIG FW 800 CARD
2 DELL 24" DISPLAYS