I'm using XP Pro SP3 too and works quite smoothly...
Already tried installing a layout with MKLC 1.4 succesfully but never came to an end yet...so I'm really glad I've been finding this marvellous forum on the net now
1) Installed the programm and assigned all keystrokes of the kyrillic symbols in wished manner
2) Vaidated the layout with some warnings left -but sucessfully as it said
3) I'm simply unable to build it or use it as assigned- because during the building process it says a problem ocurred which is a tiny window that says:
"Standard Output information"
CL.EXE returned 1
RC.EXE returned 1
LINK.EXE returned 1
..so there's only the option to click this damn OK like - It's sink or swim.
P.S.: I also tried a layout without any warnings which ends up in the same warning window..
For any help to this matter already now my special thanks!