Three machines and a BT Home Hub. All three can use the Internet OK. PC A is connected by cable to hub and runs XP. Laptop B is wireless and runs Vista. Laptop C is wireless and runs XP. All three use the same workgroup MSHOME.

Laptop C can see shared folders on all machines
Laptop B can see Laptop C but wants to open Media Centre if I click on it and will not see PC A
PC A can see shared folders on Laptop C but not on Laptop B

I've tried every combination of the settings in the Network and Sharing Centre on the Vista Laptop B with the firewall on and off to no avail.
I've tried the email settings on the Vista Laptop B which work on PC A but I cannot collect the email.

I conclude this is a Vista problem - any ideas?

sorry can you define "bt home hub"...now assuming that this hub has some sort of aerial hanging out, if not, how are the other wireless laptops connecting to pc a?

how are all pcs connected to the internet?

never hurts to check the ol event log, may provide some useful information.

Assuming you have Network sharing and discovery properly enabled on the Vista system, and all systems have identical "workgroup" names -- it helps if you have identical User Names and Passwords for the systems that want to see each other -- especially where Vista is concerned.

The XP systems should be able to see Vista on the Network, if not access it, in any case. If it is not being "discovered" try this from XP: Start > Search > Computers or People > Computer > Vista's Computer name.

You also can try this on Vista if the attempt to access is getting "denied":

run gpedit.msc > Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options > Accounts :: UNcheck Limit local account use of blank passwords to console login only

You should also try to workout whether the problem is related to wireless settings. Since wireless routers have the ability to connect by wired connection -- if it is practical -- try it.

Othe issues may relate to router related encryption and passwords for wireless systems, known as "WEP".