Cygwin

Brief

Cygwin is X for windows.

Dependencies

Configuration

Downloading from the web (Cygwin setup.exe)...
>"Select Package" various features are preselected
Note: You can click on each "Category" and
examine the preselected features.
>"Select Packages" select to add X11
Note: If you have already downloaded Cygwin, 
you can just add X11 and continue the install.

Example

Cygwin (icon)
>startx
>xterm&

Performance

With the addition of the X11 packages, I find that X GUI performance to i5/OS can be fairly good.

Reference Links