What power PSU?

I am trying to decide what Mesh to buy to use primarily to edit video and I see that it is recommended that such a computer should have a Dual Core Processor, 2GB RAM and at least 305 GB Hard drive with a separate Hard drive recommended.
Two questions:
1. It would seem that most of the computers that I look at have a 250Watt PSU. Is that the standard, if so why and will 350Watt be enough for this specification?
2. Bearing in mind the adverse comments that I have read on Vista would such a specification run efficiently?

the spec will be fine for vista. As long as the graphics card in your spec isn't fairly low powered. geforce 7600..7900 maybe the 350w will be fine. I'd be very reluctant to put a 250w psu in it though (unless you meant 350w..it is worded so that you probably did)

Mesh should make sure that the PSU is powerful enough for the specification you choose so you should not need to worry.

Also there is no need for a seperate hard drive if you already have a 300GB one.

Take a look at the Dell offers atm.
They simply cannot be beaten for price, especially if you arent gaming.

Blitzens right..Dells are cheap, solid and come with great warranties.

Check the discount store too.