To install Visual Studio 2008 Professional Edition, you need:

Software requirements:

32 bit OS: Windows^® XP Professional with Service Pack 2 installed, Windows Server 2003, or Windows Vista

64 bit OS: Microsoft Windows Server^® 2003 with SP1, Standard x64 Edition (WOW)

• Microsoft Windows Server 2003 with SP1, Enterprise x64 Edition (WOW)
• Microsoft Windows Server 2003 with SP1, Datacenter x64 Edition (WOW)
• Microsoft Windows Server 2003 R2, Standard x64 Edition (WOW)
• Microsoft Windows Server 2003 R2, Enterprise x64 Edition (WOW)
• Microsoft Windows Server 2003 R2, Datacenter x64 Edition (WOW)
• Microsoft Windows XP Professional x64 Edition (WOW)
• Windows Vista

Client software prerequisites: Internet Explorer^® 6.0 with Service Pack 1,
Microsoft Office 2003 with Service Pack 1 or
Microsoft Office 2007, MDAC 9.0, .NET Framework 2.0

Hardware requirements:

Minimum: 2.0 GHz CPU, 512 MB RAM, 8 GB HDD
Recommended: 2.6 GHz CPU, 1 GB RAM, 20 GB HDD