Would going 4/3 be a mistake?

I'm thinking of purchasing my first DSLR (yes like the rest of the world, I know) and am impressed by the Oly E510. Live view and IS are what really grabbed my attention. I had been thinking about a Nikon D300, but financially, I just can't do it yet. Then I found the E510 and was quite impressed, especially by the live view in a camera that price (I shoot a lot of macro) and in camera IS.

However I'm not so sure about the 4/3 system, it seems like a strange aspect ratio to me for still photography (and I use to work in television, which was at the time all 4:3, so I know what it looks like) and the availability of lenses worries me a bit.
Also could 4:3 be the Beta/MiniDisc/Dreamcast of photography? Am I going to drop a lot of change on glass that will be useless in 5 years?
(I'm not trying to rag on 4/3 here, I just don't know much about it)

I shoot a bit of everything, especially macro, landscape, wildlife and sports (skiing, mountain biking). So I will need to buy some fast (and possibly long) lenses, which makes the price of the body that much more inviting. I have been using a Canon S2IS.

Thanks for the help/opinions.

The 510 was my second DSLR the 500 my first. I came from many years of shooting 35mm film and hardly noticed the ratio change. In my opinion the IS technology is worth every dime extra I paid for it. If I had to change brands tomorrow I would still go with something that had in body IS. When I first purchased the 510 I was leary that the IS would even work but now feel it is the future of DSLR's. Glass for the Olympus wasn't a problem for me at the time even though it was more expensive and in short supply. But Sigma has came out with and coming out with more glass for the 4/3rds system and prices and suppy will certainly improve.
I give Olympus 5 stars on the 510. I can't say enough good about it. The image quality is wonderful too.
Good luck with the choice and let us know what you do. But take it from me, I never even noticed the ratio change. You will probably notice it more if you have lots of prints made of your work. Cropping them to fit a specific ratio.
By the way I have shot at speeds as low as 1/4 sec and can shoot at a 1/10sec while drinking coffee. You can't shoot that low with a big zoom I am sure but the IS will certainly help.

I don't think it would be a mistake. I just shot an afternoon of short track racing (Keyesville Classic) with the Olympus E-3. Although I tend to crop the Four Thirds images to be more rectangular, I don't see any reason why the system would disappear now. Olympus has invested a lot in it, as have Panasonic, Leica, and Sigma. And it's not like Betamax where people have to choose one or the other. Every camera company has their own system. So no matter what you buy into, you're making a commitment to only one format. And if you like to ride with a camera, I think you'll really like the E-510. The small size, built-in image stabiization, and 2x crop factor make the E-510 a powerful little DSLR. If you want an alternative, take a look at the Nikon D40, D40x, or D60 and the 18-200 CR Nikkor lens. That makes a very powerful mountain bike camera package, although it doesn't offer live view.

Everyone else has listed OK things about 4/3. But you do have to know the downsides as well.

The two biggest problems for me with 4/3 DSLR are:

1. Higher ISO noise than the competition is a problem for me. I've gotten used to having high ISO as an option. In my film days, I hated going beyond ISO 400. Now, I have an entire range of options open to me.

2. Restricted dynamic range. While other manufacturers are slowly increasing dynamic range, Olympus is reducing theirs. For me, this is not a good thing.

Remember, any improvements made to make the 4/3 sensor better can also be applied to larger sensors.

These two show stoppers for me may not affect you. But they should realistically be taken into account along with all the good qualities.

Thanks for the tips.
The more I read now, the more indecisive I get. High noise at longer exposure times and a lack of dc power input are now steering me away i think. I want to try doing some star photography.

Now I'm thinking about the Canon 40D, but am still on the fence, the E510 is a hard to beat camera for the price.