My boss was using GoToMyPC over aircard to access his computer. It seemed to be too slow for it to be usable. The Aircard offered 188 Kbps. Is there a remote desktop with lower bandwidth requirements that would be usable with this service?
In general: Citrix < RDP << *VNC
That is, Citrix generally uses less bandwidth than Microsoft's Remote Desktop Protocol, both of which are far more efficient than any VNC variant. The primary reason for this is that VNC has to send pictures of the desktop across the link while RDP & Citrix try to send drawing primitives. (e.g. "draw a box of this size at these coordinates" vs. "here's a (compressed) bitmap of a box to draw")
If you really have to use VNC, UltraVNC with the mirror driver option is the fastest of the bunch I've ever seen. I've never had to test it over a bandwidth-constrained link though.