The 90-day Trial of Windows 7 Enterprise is still available 32bit and 64bit.http://technet.microsoft.com/en-us/evalcenter/cc442495.aspx
To burn it to a disk after download you will need ISO burning software.http://www.magiciso.com/
Magic ISO is free.
When the 90 day evaluation trial period is almost expired or ended, log on to Windows 7 desktop, and open a Command Prompt window (i.e. type Cmd in Start Search and hit Enter).
Type or cut and paste following command into the command prompt, and then hit Enter:
Note the space in front of the forward slash. Has to be exact.
You can rearm at least 4 times= 1 year.