Hi--when I get my bike into high gear, the chain skips. I dunno what gives. The chain isn't stretched, and everything is new except the derailler. Here are the specs:
-new generic 3/16 chain
-xt rear der
-7sp cassette & shifter


Advice please!

Skipping is usually a sign of: 1) chain wear (doesn't sound like your case), 2) bent derailleur hanger, or 3) cable has stretched and needs adjustment.

See if your derailleur is "lining up" okay when looking from the back. But my first guess would be tension adjustment, especially if your bike is relatively new (ahppened to me after a few months).

Check either/both sheldonbrown.com and parktools.com on more details.