Its an ACER brand computer with a built in wireless adapter. It is running XP, latest version.

Was using a different ISP before and had a linksys router. Now I switched to ATT wireless but when I disconnected the linksys router and switched to the ATT wireless router, my computer can't see my wireless connection.

Why is this happening, what should I do to get it working

What type of wireless router is your AT&T one? Is it B, G or N? Does it support all of them or just some of them? What about your adapter on your computer? Which ones does it support?

Is the AT&T wireless router have the SSID hidden or is it being broadcast?

Problem solved for right now, there was a box in my settings that I had forgotten to click. The box was meant to let the computer connect to the wireless adaptor