Upgrading my dell graphics card

[sic91]

I have dell dimension 5100 and im going to upgrading my graphics card but i don't know ifs compatible. Its the evga 9800GTX+.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130376
Will a 500 watts power supply be good enough to run it?


Im also buying (drive) http://www.newegg.com/Product/Product.aspx?Item=N82E16827151161 and (power supply) http://www.newegg.com/Product/Product.aspx?Item=N82E16817171018
and (windows vista 64) http://www.newegg.com/Product/Product.aspx?Item=N82E16832116488

Secs for dell http://reviews.cnet.com/desktops/dell-dimension-5100-pentium/4507-3118_7-31429803.html?tag=mncol;psum
Is the evga 9800gtx+ a lot better then the 9800gt?

,thank you

 

[delluser1]

Dual slot cards won't fit.