Interesting remarks on everyone's part.
Cisco uses x86/x64 servers for most of their voice and collaboration applications (CallManager, Unity Voicemail, IPCC contact center, Presence Server, etc). They've OEM'd a bunch of servers from IBM and HP (even Dell once). Most if not all MCS servers are IBM System x or HP ProLiant servers with a Cisco bezel.
This particular machine was obtained for a steal on eBay because nobody knew what it really was. This machine is actually an IBM x3200 type 4362 (Xeon 3050, 2GB RAM, 160HB SATA HDD). Nothing more, nothing less, except for the front bezel. This was one of the very few tower servers being recased by Cisco. Good server, bad workstation (ATI ES1000 on-board video and no PCIx16 slot)... I bought it because it was a tower and it was dirt cheap compared to a similarly-configured x3200. Lovely machine, makes for good conversation!
Why did Cisco do this? Simply because a Cisco-branded server is a standardized configuration and can be covered by a Smartnet or other service contract, which often inclused next-business-day hardware replacement, just like routers & switches. Makes for an easier support process for Cisco VoIP customers.
(Yes, I deal with these systems on a daily basis.)