I gues it would work, but the vid card and the other parts wouldn't get as much power as they need and wouldn't work to their full potential. Also that would mean that the PSU would need to work 100% all the time, which would put huge stress on it and eventually destroy it.
So I'd get a new psu, something like 450W because then u have some room for future upgrades, and it's not smart to have the psu running at 100% all the time. And they cost something like $80. Check www.newegg.com
, they have very good prices in there.