Hi Brian,
We do use Citrix on top of WinNT-TSE or Win2K for our VFP7, you noted VFP6, apps. We've ran into some problems that the IT guys may be thinking. These KBs should help you out with some. The first problem almost always rears its head while the second one will on ocassion.
Microsoft Knowledge Base Article - 176483
PRB: Large Amounts of RAM Seem to Process Data Slowly
Microsoft Knowledge Base Article - 818528
Problems When More Than One User Accesses the Same File Through Terminal Services
There is a thread here that details VFP's effect on memory and the reported usage by the server. I forgot the thread number but I have the snippets of the thread saved. I can email it to you if you want.
HTH.
ramil
~~ learning to stand still