WIndows XP/Vista Networking.

I know there has been a lot of posts on this subject, but none that have
helped me so my apologies if this is redundent of past posts.

I just bought a new Vista Home Premium HP laptop. Got it on release day, Jan
30. It refuses to see any XP computers on the network.

I have internet access, it works on the vista laptop, but cant see any
non-Vista computers on the network its accessing the internet through.

I tried installing the LLTP protocol on one of the XP computers..no go.
I tried taking down the firewalls..still no luck
All computers are in the same workgroup
Network discovery is on and all the file/printer/media sharing buttons are on.
XP computers are XP Pro.
tried connecting through different lines/wireless routers on the same
network(I am in a fraternity house and we have 3 wireless routers all
connecting to the same base network/internet router.)
The XP computers can see my vista machine, however.

One of my brothers was a Beta tester for Vista and has been running vista
for some time. He has ultimate and can see everyone,(even the XP Pro comps) I
can see him, and he can see me, but I cannot see the other computers. He has
taken a look at my laptop and is just as confused as i am in this matter. He
has no idea why my Vista laptop wont work.

Thanks for any help
Bob