Is my OS using my ram like it should?

yannifb

Distinguished
Jun 25, 2009
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OS: Win. Vista Ultimate 64bit
8gigs of ddr3 1600 OCZ gold
AMD Phenom ii X4 955
GTX 295
MSI 790fx GD70

Now when i look at my task manager the usage of the ram never goes past 1.77 gigs. It says
Total: 8189
Cached: 6822
Free: 51

Is it using it all?