Help With Powerbook Cpu Options

[mishmashmole]

Please help. I bought my band new 1.5 GHz/ Superdrive/512 ram) os x 10.3.8 powerbook in Jan 2005. There were so many reasons I bought it. For so long I wanted a portable computer that worked, rather than my old windows brick.
I think something must be wrong or the answer is more memory. I want to use Ableton Live but as soon as I start using VST then the computer really starts to struggle. The CPU meter gets up to 100%. I have found the cpu getting this high and staying like it in other apps too, non-music ones. Even now writing this, I only have Live (not actually playing anything), Stcikies and Mail open. The cpu is staying between 65% & 70% and the RAM used is 352MB. This can't be right. What am I doing wrong? I can only think it's beacuse I have installed so much software, (and taken it out), that I need to do a fresh install and see if it's still the same. Thanks all for your help in advance. PS I just switched to MAC 4 months ago!