You have many questions young one . As for your specific query, I would say *hopefully*. Bare minimum these days is about 350W, with 400W being preferable.

As Esq said, the higher watts, the better. You then have power to spare, rather than taxing the equipment.

IMHO, go with at least a 400, because you're going to want to upgrade other components as well. In the meantime, here's a quick guide (Courtesy of TigerDirect.com):

Component Wattage Required
Motherboard 15-30
Low-End CPU 20-50
Mid To High-End CPU 40-100
RAM 7 per 128MB
PCI Add-In Card 5
Low To Mid-Range Graphics 20-60
High-End Graphics 60-100
IDE Hard Drive 10-30
Optical Drives 10-25

A 300 watt PSU is the recommended minimum for the X700 PCI-Express bus as well.

But I think the others here are right. You need some headroom. If not when you have bought the X700 soon after, you should consider upgrading your PSU to at least 400-450 watts. I'd look for something with even more capacity but that's up to what your wallet can handle.

sound advise there from the Insurance fella, watch he doesn't try to flog you any warranty policies written on toilet paper though Incredible to think that only a few years ago he didn't even know which way round to hold a screwdriver and was in Dell-Hell

with a hungry powered card like that, DVD drives, cpu power, and everything else, you ned to cut yourself some slack. Don't go for less than 450W, pay the extra few quid, you won't regret it. Enermax, Antec, any decent name but not cheap rubbish from China that gets shoved in bog-stadard cases. I use an Antec 550W Trupower in Borromir (and I have 700W Liebert PSU behind it as well)