Hi Tony,

I've never done heavy work with music software sequences, but I've had a dab with quite a lot, and done small projects with a few.

The programs I loved using the most, and found most intuitive, appealing and inspiring were all the cheapest ones (or free!)

Mackie Tracktion (I got a free copy which they gave out a year ago)
Fruity Loops (about 50-150 GBP depending which version)
ComputerMuzys (free with every computer shopper magazine but a admittedly fairly limited)

People will say these are more like toys, but I found myself more productive with these than with Sonar and Cubase (which I really forced myself to learn on a Mac - brought a FastGuide book etc - but never liked it). Depends what kind of music you're making obviously.

Audacity of course is a great audio program everyone uses all the time and is free.