Your MB info (don't pay attention to the missing fonts, just click by them and start page flipping)
http://www.mafiaowns.com/mfs/files/file_info/download.php?file=Intel_PRO_6_4_14_0_readme_en.rarI think you will need that info, if for anything to make sure you don't have to go into the bios to turn of the on board video and to check ram timing/ram setup.
GPU, that will work
http://www.newegg.com/Product/Product.aspx?Item=N82E16814103167If PSU is needed, that will work
http://www.cputopia.com/emachine-480w-t-series-t3958.html (I assume you are going with the e-machine, just in case it is needed from the same company?, no problem its only $20)
Sure if you want to have 2g of ram, but get a matched set
http://www.newegg.com/Product/Product.aspx?Item=N82E16820178101 or pick what you wish from this list
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=2010170147%201052107965%201052308477&bop=And&Order=PRICE&PageSize=20Will it run run, BF42? Yes, I have a computer here that only has a intel 1.8 with 1g of ram with a ATI 9000 GPU and it run BF42 just fine, BUT it isn't to happy with extra video settings, Higher AA and AF, anything over 4x AA and AF, means bad FPS.
But really, I know money is money, but by the time you are done, you can buy a new "cheep" computer...
Same cost of your parts...
http://www.newegg.com/Product/Product.aspx?Item=N82E16883103228 (more a less a lap top, maybe a netbook? turned into a desktop)
$100 more then your parts...
http://www.newegg.com/Product/Product.aspx?Item=N82E16883109039$200 more then your parts...
http://www.newegg.com/Product/Product.aspx?Item=N82E16883114083I am not saying the above is the greatest, but I think I good match (if not much better) to your plans of buying new parts.
Just my thoughts on it all, others thoughts I am sure will differ from mine.