Preinstalled 32-bit: Genuine Windows XP Professional Service Pack 2 (WHQL certified) Preinstalled 64-bit: Genuine Windows XP Professional x64 Edition (WHQL certified) Window Vista Capable Tested on Genuine Windows 2000 Professional SP4 Preinstalled Red Hat Enterprise Linux WS 3 (64-bit only) OR HP Installer Kit for Linux (includes drivers for both 32-bit and 64-bit OS versions of Red Hat Enterprise Linux 3 and 4) Certified on Red Hat Enterprise Linux WS 4

The HP xw4300 supports Extended Memory 64-bit Technology (EM64T) which extends the address space to a maximum of 16 TB virtual memory, allowing for the design and manipulation of huge data sets or models. An EM64T enabled workstation should provide leading performance for many 32-bit applications.