download, install and run ccleaner (google it).
In addition you may want to get rid of some old system restore points (not sure if ccleaner does this).
Right click on the drive and select properties, on the general tab click disk cleanup, switch to the second tab and use the bottom option to remove old restore points.
Intel core I7 920
6GB OCZ platinum 1600
Samsung 1TB F1 Spinpoint
Samsung SM2443BW 24"