In my opinion, your best bet as far as a body/lens combination both for today and down the road the Minolta is the best choice, with more options as far as lenses, both third party and OEM and... to be honest, a better future. The 4/3 format isn't exactly setting the world on fire. The E-1 is a little long in the tooth. If you can live with it's performance for a few years compared to what is going to be available then it's probably an OK choice. Today it's priced right, but ONLY because it's probably about to be replaced. Back when it was new it and it's lenseswere very expensive (body only was $2,000)compared to it's competition and in all liklihood it's replacement will be too because it will not be a high volume item and the company will need to make hay while it can from the (few)people who do buy it.
Yes, you will need to go to ISO 800 if you plan to shoot low light without flash- probably ISO 1600 too, and the Olympus sensor performance as far as noise goesis far from the best option for that type subject.