Does your company operate a Citrix or Terminal Server ? if it's a windows 2003 I think you should be able to install the SQL 2012 tools. Maybe have a look about virtualization on the XP desktop side ? install a Win7 VM with the SSMS 2012 tools.
I use Win7 64-bit and was surprised to not be able to install SSMS 2012 (final RC) because my system is not SP1 applied... but I was able to install the CTP version of the tools... this version works fine, so it's only a question of validation prior to the install that keeps the final version to install on my system.
Have a great day,
Sr. System Admin & accidental DBA