I bought a motherboard nvidia nforce 730i I'm having hard time finding the right software it's say in the box micro soft windows vista capable, is this means that I can only use windows vista instead of windows 7... please any expert who can help me...

Have you gone to the manufacturers website to see if Windows 7 drivers are available for it yet? And download them all if you find them. THOSE will likely be more up to date than anything in the package are anyway.

Some Vista drivers work under 7, but its best to use true Windows 7 drivers.

You can't assume they took the time to write them... I've seen cases they didn't.

I would definitely contact the manufacturer in this case. Motherboards are a pain to get the right software/drivers for, so check with them first, then run Windows Updates and see if it can detect your graphics card, or Google Nvidia card detector and see if it can find the drivers for you that way.