When I built mine, I used Tiger Direct. 

Just a few items that may help get you started:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3265523&amp;CatId=114

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=2782551&amp;body=MAIN#detailspecs

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1462306&amp;CatId=114

Need to get an new Vid Card with the last two, they sell them also.


A quick look on Dells site:
http://www.dell.com/content/products/productdetails.aspx/inspndt_53x?c=us&amp;cs=19&amp;l=en&amp;s=dhs&amp;~tab=bundlestab

Options, options.

Z