Slow speed video + running games

Hello,

heres my pc spec, im not sure if its the correct forum,
http://www.tigerdirect.ca/applicatio...312&CatId=4928

the only thing I replaced was this
http://www.tigerdirect.ca/applicatio...ampaign=CANLET

im running the last windows patch and driver for everything direct x , 3d card

I used to run games like skyrim or team fortress, with decent definition with no lag , now I cant even run it, its very slow, cant even play it, even when watching streaming video online, its lagging out

I have the minimum program running in backgroup, I recently did a format, I try to keep it simple on it , most settings on performance

Any idea how to improve this ? Id like to play games and run them smooth, my budjet is a bit limited and my skills

Any guides or ideas programs, what to do, or hardware to replace, cheap scenario prefered, I still want to keep it

Thanks a lot