I tend to beat this to death, but that is why I use an OLD linux box.. Pentium II, 512 MB ram. I run it in a corner of the room "headless" (no monitor or keyboard) and log into it via SSH. Since switching over to pushing the broadcast to RR I am using about 40% of the CPU and it runs 24/7 with no issues. Power goes out, no worries (has only had one power outage UPS didn't handle in the past 2 years) it comes back up. Patches to the O.S. / Reboots if necessary are handled by cron jobs. Down side at this point is still have not gotten text tags working, but intend on doing that someday.
I will admit, it's not as "plug-n-play" as some people would like, but the point really is you don't need to use much of a box to dedicate it to streaming, and it's more reliable than the windows solution. I would be happy to help anyone who would like to take the plunge and try the alternative method. I don't know if there is anyone other than me doing it this way on RR (at least they aren't as vocal as I tend to be)..
If you continue to have problems (yes, windows is prone to memory leaks when not fully patched up, XP pro can run quite some time, but will still need the occasional refire) shoot me a message if you want to try the alternative method I use..
Otherwise, make sure you have all of the updates and patches for windows, and the latest audio drivers for what ever sound system you are working using (some of the early Realtech drivers were very prone to memory leaks).
Good luck!