If you can tell us what partitions you have, then we can better understand how to help you.
Click the 'Start Orb'
Right click on 'Computer'
Click 'Manage'
In the 'Computer Management' window, the lower left, under 'Storage', click 'Disk Management'
You will see the Hard Disk information there. Give us the information at the bottom as it is listed from left to right, or give us a screen shot.
If your empty partition is on the right side of your operating system partition, then it can easily be merged using 'Disk Management'.
Go to the Seven Forums tutorial:
How to Extend a Partition or Volume in Windows 7
If it is on the left or before the operating system partition then you will need a Partition Manager program.
You can find a couple of free partition manager programs that will do the job for you. This Seven Forums site has an extensive list of free programs that work with Windows 7.
FREE Great Programs for Window 7
Among others you will find:
EASEUS Partition Master Home Edition
Partition Wizard
I have used both of these and they work very well. Partition Wizard is compatible with 64bit and works with 32bit also. Either one will get the partitions adjusted for you.
Any questions, just reply here.
If you want to find all your system information and more:
SIW - System Information for Windows
You can use this to fill in your 'My System Specs' or maybe an easier way is to go to the 'Start Orb' and enter 'dxdiag' in the 'search Programs and files' box, click 'dxdiag.exe'. This will give you the basic info needed. This will help people here, help you.
Another Seven Forums thread for 64 bit Windows 7 free programs:
Free 64-bit programs