If you're going over budget already, I'd double check with him and find out his absolute maximum budget (S&H and all) and see what components he's willing to drag over to the new build (hdd, optical, etc)
If we can re-use the harddrive and optical, you should be fine.
Any reason he doesn't use ATI? I used to be biased towards Nvidia after 3 ATI cards (on a failing mobo) caused hive cluster crashes in XP, then went to Nvidia and had great luck, but my new x1900gt runs great, ATI really improved with their x series graphics cards, I'd recommend at least giving the options, because you can get a much quicker video card from ATI for the mid-range than you can Nvidia.
E6300 is a great way to go, but on a budget system, I'd recommend 4300 instead. Look for the AsRock 775 C2D board, should be around 60$ newegg.
If you go with a higher video card, or more devices internally (fans, optical drives) go with a power supply with a higher 12V line, or multiple 12V lines (2 12V 14A rails = better than 1 20/22/24A rail, more stability)