No, get a new PSU. This is as dumb as the guy asking if his 200W PSU was enough for his 7600GT. Get what is recomended, and stop asking stupid questions. Sorry to sound a bit harsh, but it's always better to be safe than sorry.
The forumz have been filled with complaints about the X1950pro, when most won't except the fact that their PSUs are insufficient.
When upgrading your GPU, you must take into account your PSU.