From your experience how well would i do in a course that i don't really like i.e engineering? I have quite a problem with calculus and some other math stuff. Unfortunately engineering tends to have better career prospects, or rather a wider variety of career prospects. Would i be able to do well for the course that i don't really like? Assuming that i work...reasonably hard. I heard that engineering aint an easy course. Combined with my loathing for calculus...

A step down from that would be the biological sciences course, which im fine with but appears to have a more narrow range of career prospects. Seem like if you don't get a PhD and be a researcher you're likely to be doing some other 'generic job' not related to your degree.

And even further down would be an arts degree. I like writing and a little freedom in it, not all the rules and 'keywords' in science, pfft. (no keywords, no marks. Zip.) Examined a salary poll on a website and it seemed like certain courses like Psychology and Sociology earn pretty well, though im not sure if they're doing work related to their degree.

There is no such thing as a course of profit, especially in bad economies. Those that choose a career for the money almost always are the worst people at that job (no passion) and therefore the first to lose the job and the worst paid.

Do a degree that interests you, not one that you think gets you a job. No point wasting 3-5 years on a degree you don't enjoy for a potential job you'll wake up every day hating.

And from my own experience, don't do engineering unless you enjoy that sort of stuff, and don't do it if you're not good at maths. When I finished High School I had about 6 of my friends do Engineering, and only 2 are still doing it (Electrical and Mechanical). The other 4 did it because it was 'prestigous', not out of interest. Those 4 all struggled through their first year (although one did go through a second year) before changing to something else. Now instead they're doing Town Planning, Science Teaching, Music Teaching and Graphic Design, and they're all much happier. Engineering degrees also have a lot of maths in them, so if your mathematical ability isnt up to par, you'll spend a long time struggling and not enjoying yourself.

Choosing to major in something for purely money is a little ridiculous, but doing a mix is possible and is what I am doing now. I have a lot of interests, I just file through which interest gives me the most money.

Don't choose a major that you don't like! That is simply a recipe for disaster, as others have noted. Instead, choose a field that you actually enjoy and work hard at it and show others your passion for it.