Vista - XP access Vista but Vista can't access XP

Okay, I bought a laptop with Vista Home Premium and I've set everything up to
work on a network.

My desktop computer runs XP and is connected (hard wired) to the internet
through my D-Link 655 router. The laptop can see the desktop computer, but
can't access it via wireless. The internet access works though.

Both have different computer names;

Both have the same workgroup name;

I can see the XP computer and can ping both computers; and

Both firewalls are off.

Have the Hotfix for XP to address this problem.

Xp computer can access Vista computer.

Any ideas??