Windows 7 laptop can not see XP computers?

My windows 7 wireless laptop does not see my XP desktop computers (hard wired to my router). My windows 7 wireless laptop can access the internet via the 2.4gh band of my new dual band router.

My XP desktop computers can see my windows 7 wireless laptop and access shared files.

I just upgraded to a new dual band router. The prior router was a single band and my windows 7 wireless laptop could see my XP desktop and access shared files.

Any suggestions as to how I get my windows 7 wireless laptop to be able to see my wired XP desktop computer?

If both computers are part of the same Homegroup, you may want to check the following settings on the both computers:

Homegroup / Workgroup (XP)

Network Sharing

If you have an Internet Security program installed on either computer, you may want to check the network protection/firewall settings.

Thanks for the two responses. Based on the suggestions, I went back to my computers an started searching and changing. The good news is that both my windows 7 and XP computers now can see each other and share files. The bad news is that I don't know what changes I made to make this happen.