Hey, I read your thread and notice you may have some small problems.
Your computer should run fine if you have a onboard sound such as realtek audio or hd audio.
Your computer has almost the same graphics card I run in my custom gateway.
I use a ATI Radeon X600, I just let windows 7 professional do a clean install on my pc and 85% of my hardware was recognized.
It installed the drivers for the video card, sound card motherboard lan port and other normal basics.
If you have any external devices such as a usb network adapter, printer thats farily new camera's and mobile phones... you might have a slight problem.
That can be temporarily fixed if windows 7 will let you do so, use combatiblity mode using either windows xp 3 or vista sp2 option to install anything that would work with proper OS settings and it should work fine for now.
Beware though you will get the "once and awhile" crash if your hardware goes berserk from some odd reason.
That case you have their is a BTX, don't think about trying to rebuild it with a ATX board because you will be very limited for awhile with mobo's.
Other than that you should be ok with installing the windows 7 OS that advisor gives you for the time being.
This is my case I used to build my 8th pc last year:
