are you saying if its ok to use a 375Watts PSU for a requirement of 450Watts?
You won't get far with an underpowered supply. You are going to have a larger supply to provide the power for the newer card especially if you try ocing with it.
Even running it stock you would be kind of lacking there. Once you started any heavy gaming or running any demanding apps like multimedia the power level would drop once the card saw a good load. That could make everything run unstable. While cpus have gone down from 1.65v-1.7v to 1.34-.14v video cards can be a little more power hungry when a good load is placed on them.
I think that pretty much sums it upare you saying if its ok to use a 375Watts PSU for a requirement of 450Watts?
well.. you could get such a fron bay PSU to power your grafic's card only..
ill have a look on what they are called again... i forgot about that
edit: http://www.newegg.com/Product/Product.asp?Item=N82E16817104019
but considering the price tag.. maybe getting a new one is the cheaper option. ( a new ATX PSU that is).. i hope your current PSU has a 20 or 24 pin connector to the motherboard? (I think it has, but i can't be sure ofcourse )
The supplies they have always used were made to fit "their" case styles not the typical case seen in custom building your own. Instead of seeing the holes on four corners they are in a square pattern to one side.
I have replaced a many DELL P/S and all of them so far has had standard mounting holes!!