There is a mature VNC client, a couple of SSH clients and a pretty poor remote desktop client (has no built in support for right clicking, on screen keyboard). I am pretty much positive that a proprietary web page embedded client will not work, as Opera does not support Active-x or Java on the N770 or N800, currently. Java support is probably forthcoming from third parties within the next few months, but I have seen no evidence of official support from Nokia on the horizon. I would recommend switching your desktop to one of the excellent and free solutions listed above. If you need help, I consult commercially.

Good Luck.