When you buy a digital SLR, you are really buying into the lens system, and that should really be an important part in making your decision.
For instance, it is no good buying a camera where lens range is limited/expensive for your needs. Remember you will may want to updgrade the body, but you can keep your lens collection for future cameras of the same make.
I would certainly do some lense research if you are considering the Olympus - not that it is a bad camera, but just check if the lens range is suitable and priced right for your individual needs. Also read some reviews on lenses for all cameras you are considering, as well as the cameras themselves.
Personally, I went for Canon mainly due to their lens range - especially the much coveted L lenses. I have the 300D and the 20D and both are very good. I find the 300D a great easy to use SLR with little picture difference from the (now old but better) 10D. The 20D is another kettle of fish, with finer control, but, to be honest, image wise, there is not a whole lot of difference.
I would certainly think of opting for a 300D or a 350XT - both of these would make an ideal introduction into SLR photography without costing the earth. Its the lenses that will eventually cost you, as with any DSLR