Photoshop :: CS4 Very Slow

I am getting lots of problems with CS4, some of which have been covered in separate topics on this forum. In the main, it seems to me that there is a real problem with CS4 processing relatively small amounts of data. The difficulties I am experiencing are:

1. Text tool very slow. Just typing a few letters sees my CPU usage shoot to 50%. There is a lag of about a second between typing the letters and their appearance on the screen.

2. Pen tool very slow with significant lag when using the mouse and CPU again shoots to 50%, even for a short line. If I use the tablet (Trust) it sometimes works, but suffers the same lag as the mouse when it does. Most of the time, though, I just get a faint straight line between the start and end point. This morning I got the same straight line symptom on the mouse!

3. Screen redraw can be painfully slow and blocky, but this fault is really sporadic

4. There is no apparent difference whether I have GPU active or not. However, I have just had a strange message. When GPU was disabled I restarted CS4 and got the message that there was a problem with the display driver, and PS was therefore disabling GPU enhancements! After that, the pen worked fine, and the mouse too, but then the mouse started losing curves.

I experience none of these problems when I run CS.

My video card driver is up to date. The trust tablet driver is the latest, but I really do not think this is the issue, as the drawing problem also affects the mouse.

System spec - XP with SP3, AMD Athlon 64 X2 4800+, 2GB RAM, nVidia Geforce 7600GT, Program on Raptor 70GB, Scratch on separate 70GB Raptor