Ok, cool. I wrote an artical about this here:
http://www.freewysemonkeys.com/site/modules.php?name=News&file=article&sid=20&mode=&order=0&thold=0
I used to use PXES before X2 got it with PC’s and Wyse 9455’s/9650’s and it worked great.
There is no reason why ThinStation should not work on a 3150 but be aware that Linux has a higher memory and CPU requirement than CE if you pack to much in. This means you will need to keep the environment small or you will not get it loaded on the terminal. The second issue is that the 3150 is a Wyse board so getting drivers could be a bit of a challenge, the 5150 is the same board with Linux so it can be done.
Good luck, and post the results working or not as I would be really keen to see how you get on!
Cheers,
-TT