Looks like 64 bit is it for version 7:
Microsoft Windows
Intel® Core® 2 Duo or better.
4 GB of RAM
10 GB of free hard disk space
Calibrated color monitor with 1280 x 800, 24 bit resolution at 96dpi screen ruling
Windows® 8 64bit, Windows® 7 64bit, Windows Vista® SP2 64bit
Microsoft® .NET Framework version 4.0 (will be installed if not present)
A PDF reader is needed to read the Release Notes
Flash is required to view the intro video
An Internet connection when activating Capture One