I tried Mono

Do you know Mono?
Mono is a runtime of .Net framework for Linux or other System V Operation Systems.

I installed Mono1.2.4 on Ubuntu 7.1.0 with apt-get.
like this

# listed below may include some unnecessary packages
sudo apt-get install mono
sudo apt-get install libmono-microsoft8.0-cil
sudo apt-get install libmono-winforms1.0-cil libmono-winforms2.0-ci
sudo apt-get install mono-tools-gui libmono-cairo2.0-cil libmono-cairo2.0-cil
sudo apt-get install libmono-system2.0-cil

And , I could use some .Net applications which have GUI with Mono successfully :-)
I suggest you to try Mono by yourself ;-)