I just used the bandwidth speed tester at http://nitro.ucsc.edu/ and our T1 had the following results:
running 10s outbound test (client to server) . . . . . 1.25Mb/s
running 10s inbound test (server to client) . . . . . . 1.46Mb/s
while our dsl line had the following results:
running 10s outbound test (client to server) . . . . . 487.18Kb/s
running 10s inbound test (server to client) . . . . . . 2.49Mb/s
So theoretically, the T1 would be better for serving out web pages while the DSL would be better for downloading. Lately, though, our T1 has been going down much more often than our DSL “backup” line.