Problems with ubuntu 11.04

[Andrew]

I recently upgraded to 11.04 from 9.10 and having some problems with it:
it seems a bit unstable (and slow), although I may be a bit 'hardware
limited' (running a rather old Dell Dimension system). Also problem
getting my HP Color Laserjet 3500 to print colours correctly despite
installing latest version of hplip-3.11.7.run
Was I ill-advised to go straight to 11.04 and should I instead go
'back/down' to 10.04 which hopefully has had most of the bugs ironed
out?

Andy