With a good OS you should be able to use Rosegarden... You won't be able to record a lot of tracks at once, and I'd stay away any plug-in that is not immediately rendered...
For an OS I'd go for any lite version of XP or a lite Debian Linux build...
Nasbi makes a good version of XP lite, but there's another build that's even better called XP-super-lite-V2 I don't know who hacked that one though...