Hey, from another Clydesdale Rider. I'm also 6', and vary from anywhere around 225 to a high of 240 lbs.

Wheels will be your nemisis. I've gone through so many I can't even count!

For $1,000 you could buy a lot of bike.

I would suggest you stay away from full suspension bikes. I know the temptation is great, but as a newbie and your budget, you'll get a better bike if you stick to a hardtail (front suspn only).

There are a lot of bikes we could suggest for you, but it won't make a hill of beans difference until you go test ride some. Visit ALL your local bike shops (LBS) and ride as many different bikes as you can.

I would suggest a beefier hardtail vs. a lighter weight XC bike. Something like a Specialized P.2, or a Haro Escape 8.3, or a lot of Kona's bikes. K2's got some decent bikes this year, and KHS has got some sweet beefy bikes.

As a newbie, I'd stay away from buying online. You really need help from you LBS when you're getting started and don't really know what to look for. Plus, they could hook you up with some local trails and perhaps a group ride. A great way to get involved in the cycling "community".