Computer laggg with a alright RIG

Ok so my rig gigabyte mobo not sure model number
6870 saphire card
phenom II 955 BE 3.2 Quad core
1tb western digital HD
6GB DDR2
770w OCZ PSU

I lag all the time...Im using windows 7 64bit and I thought my rig was ok not the greatest bit ok please try and help me out I play MW2 mainly but also amnesia,dead island,ut3,gw and I lag on them all my internet Is only 1 MB upload speed which sucks but even games that dont req internet lag Im lost and dont know where to look I did the windows 7 thing where it scores your computer the max is 7.9 my GPU is 7.7 my cpu and ram are 7.1 but my hard drive is 5.9 i dont think that would matter but Im just giving you all the info I can when I play MW2 if I use frapps its a little worse not much but even when I turn the graphics real low I till get lag I dont know if its my HD, or RAM maybe even my cpu the video card is 2 weeks old the hard drive is about 6 months old and the cpu and ram were bought about 1yr and a half ago any tips at all would be greatful thanks in advance

6 gig of memory on amd are they dual channel or you board use something else