The minimum system requirements for Web Designer 9 and Web Designer 9 Premium are: 

Windows XP, Vista, 7 or 8.  

500 MB RAM, 

300 MB hard disk space.

Intel® Celeron® or newer, or AMD® Sempron® or newer.

Both Web Designer and Web Designer Premium work with 32 bit and 64 bit Windows, but Web Designer 9 Premium has a separate 64 bit version that uses the extra power of 64 bit to give the best performance for large, content rich sites.