Like I said, mine locks a lot better now since the T Mobile update but the performance on it blows about as much ass as Oprah after eating some Wendy's chili.
Stop sitting around getting satellite locks and try using the GPS on the road
Going into the secret GPS settings and messing with the SUPL settings etc were first reported to help a long time ago after the phones came out but never really helped at all to be honest. In fact Samsung came out with an app to put these settings back to the default after people messed with them and found it didn't help. I tried changing it to google and it seemed to help for a few days but it went back to the same old crappy performance. The only thing that helped with the locks was the official fixed rom that came out a while back. The locking is still a little slow but it locks on a lot more sats when it does lock now. My issue is with the tracking when actually using the damn thing on the road.
The unofficial Froyo roms may make the GPs perform better though.