The Olympus cameras have (from all reports) really nice kits lenses. The downside is that, because of their smaller sensor, Olympus cameras have more image noise at ISO 400 and higher than Canon, Pentax, Nikon, Sony, etc. If you do primarily daylight shooting, or use flash, this is not much of an issue.
I agree with twistedlogic that it can be beneficial to play with a camera before buying. That said, I had never touched a Pentax prior to buying it online, and it fits me just fine. I'm the type of person who adjusts to different things pretty easily, but if you have a finicky-type of personality, you probably should try to handle as many different cameras as possible. Pentax has a reputation for very comfortable bodies - solid, not too large, not too small.
I also agree that there's not much difference in image quality (IQ) between similar cameras. Images from a Pentax K2000, Nikon D60, Canon XS all look pretty similar, when using similar lenses.
The major benefit of in-body image stabilization is that ALL lenses are (or can be) stabilized. With in-lens stabilization, only certain lenses are stabilized. The major negative of in-body stabilization is that the camera's viewfinder is not stabilized, which doesn't affect the picture, but it might be distracting for the photographer.
There's an adage among photographers: "you don't buy the camera, you buy the system". The essence of the comment being that once you buy the camera body, lenses, flash, etc. you can't easily switch to another brand - you need to start from scratch. It's much easier to switch brands now than it was 10 years ago, as with the advent of Craig's List, Ebay, Amazon marketplace, etc. it is pretty easy to sell camera gear.