Can this be done?

Ok i have my old rig(q9450,4gb ddr2 1066mhz,gtx460se),which my sister is using right now,but when i move out it is coming with me,and i plan to use it as a multi use system(steam box,nas,htpc).

Other than the gpu i have a tv tuner,an ide card(most of my extra drives are ide),and mabye a sound card,but i was also thinking of doing something else i have a ati aiw x800xl (http://www.newegg.com/Product/Product.aspx?Item=N82E16814102582) and i was wondering if i can put it is the second pci-e x16 slot,and use it just for the tv tuner,so i can have dual tuners.

Can it be done? If so how?

Well there should be no issue with having dual tv tuners in one PC. Just an issue with what software you use to view the information they are spewing out.

Maybe it is as simple of just running two instances of the tv tuner software?

You can use as many tv tuners as you want on a system with just one graphics card. The software should be able to for example record from one while streaming to you from the other (but this is a software problem, so it depends on the software you're going to use)

Well the x800xl is a gpu with a tv tuner on it,that is why i am wonder it will work.