The next thing would be to check the MTU settings on both - My XP Pro is 1300. Now I haven't looked at this since 95/98 times, but as I recall the optimum setting was 1500. Check what it is in 2003. There are tools around for this, but most are old, I can't see anything I would care to use on XP at this point. Anyway if the settings are the same then this isn't the problem. If you do a regedit search, the MTU settings are towards the end, so it will take a while to get there.