Below it's system requirement
Clients
- Microsoft Internet Explorer 6.0, 7.0, 8.0, 9.0
- Mozilla Firefox 3.0, 3.5, 13, 14.0
Physical Appliance Deployment
Hardware options (Hardware purchase is required):
- Symantec Web Gateway 8450
- Symantec Web Gateway 8490
Virtual Appliance Deployment
VMware ESX 4.0 or 4.1/ VMware® ESXi 4.0, 4.1 or 5.0
- Microsoft Internet Explorer 6.0, 7.0, 8.0, 9.0
- 64-bit
- Intel virtualization technology enabled
- Virtual Machine (VM )Requirement
- Two Central Processing Units (physical or logical)
- At least 8 GB memory
- 120 GB disk
http://www.symantec.com/web-gateway/system-requirements/
System requirements for Symantec Web Gateway Virtual Edition
https://support.symantec.com/en_US/article.HOWTO54166.html