Or you can copy from Vista SP0 for the four files of RDP as indicated below.
File Location
mstsc.exe c:\windows\system32
mstscax.dll c:\windows\system32
mstsc.exe.mui c:\windows\system32\en-US
mstscax.dll.mui c:\windows\system32\en-US
Actually, the above files for RDP can be run in Vista SP1 without problem. You can copy them to a thumb drive or any folder in your local drive; create a shortcut for mstsc.exe and use the shortcut to connect to your XP media Center.
For example. you can put the mstsc.exe and mstscax.dll in a folder, say x:\RDP\ and put mstsc.exe.mui and mstscax.dll.mui in a sub-folder, say x:\RDP\en-US. Assume x is the drive letter for your thumb drive.
In doing so, you have made a portable RDP client of your Vista SP0 and the said RDP client can be used on any Windows based machine (from XP onwards).