Hi there rengle02,
As far as I understood, I think you have two problems over here.
1st one: You see only 750 GB out of 1 TB. You need to go to Disk Management and see whether you have some unallocated space over there(250 GB). If this is the case, you can just extend your partition(right click -> extend partition). Check this out:
http://www.sevenforums.com/tutorials/2670-partition-volume-extend.html
2nd one: Something on your drive is taking a lot of space. My guess would be that you may need to adjust your System Restore settings. Delete previous restore points and reduce the HDD space allocated for that. Check this out: http://www.howtogeek.com/howto/5482/make-system-restore-use-less-space-in-windows-7/
Hope this will help,
D_Know_WD