Do you have hibernation enabled? How much RAM do you have?
Disabling hibernation will give the amount of RAM you have back. 8GB will give you 8GB back.
Go to the command line and type powercfg -h off
You can move your page file to another partition. I did this with my SBS Standard since my page file was 24GB (1.5xRAM amount) due to the 16GB of RAM. That cleared my drive right up.