Yeah, stick with the 300m, it's seems like a good choice for you.
The T41 definitely IS absurdly expensive, but you have to take in account IBM's excellent service and build quality. It has a cd-drive like all laptops, and is only 1" thick. The whole thing is extremely solid built, and will last for a LONG time. Dells have been known to have quite a few problems.
But since you're getting discount on the Dell, go with the 300m, it's thinner and is a better solution for mobile use. 512 ram is recommended, the higher the better.
