Also, you may want to set your border router (the one with the serials to your ISP) to route "per packet" as opposed to allowing the routes to cache. This will distribute the bandwidtch evenly across your T1's. If you don't, then a single high traffic session or destination can consume an uneven amount of bandwidth on one of your lines. You can ask your ISP to do this as well for incoming packets.
-=Vandy=-