WebSphere Application Server is supported in the following environments:

• AIX (32-bit and 64-bit WebSphere Application Server)
• HP-UX PA-RISC (32-bit WebSphere Application Server)
• HP-UX Itanium (64-bit WebSphere Application Server)
• Linux on x86 (32-bit WebSphere Application Server)
• Linux on AMD Opteron and Intel EM64T (64-bit WebSphere Application Server)
• Linux on S/390 and zSeries (32-bit and 64-bit WebSphere Application Server)
• Linux on POWER (32-bit and 64-bit WebSphere Application Server)
• OS/400 and i5/OS
• Sun Solaris (32-bit WebSphere Application Server)
• Windows Server 2000 and 2003 (32-bit WebSphere Application Server)
• Windows Server 2003 x64 (64-bit WebSphere Application Server)
  

Refer to the following URL for the latest information on the detailed system requirements and software prerequisites:
http://www-1.ibm.com/support/docview.wss?rs=180&uid=swg27006921