I think for your solution you are looking at a XenApps deployment, do you already have a server running 2003?
This solution is not cheap, so you will need to do some analysis here.
Citrix XenApp with 5 licences for windows 2003 will run you about $1200
If you dont already have a server then you are looking at another $2000-$4000 depending on your needs
Some good info:
http://www.vb123.com/toolshed/05_access/remotedesktop.htmhttp://store.citrix.com/store/citrixus/en_US/pd/productID.194911600http://www.granite.ab.ca/access/terminalserver.htmhttp://forums.citrix.com/thread.jspa?threadID=238434&tstart=0