I have acer 6530 G and installed xp in place of

Try to contact your dealer about your problem. Second, if you can access through the internet using another computer to download drivers from or the ACER SOFTWARE for your acer 6530 G so that it will solve the problem. Though you have shifted OS from Vista to Xp as long as you have drivers for your Pc it will certainly work fine.

you need to install the xp drivers!! here is the link to acer and the 6530-6530 g drivers.
You may need to remove you covers on the underside of the laptop and look the make sure you use the right drivers, as acer puts more then one type of hardware in you laptop. IE you may have the (Ralink) wierless card or you may have the (Atheros) or (Broadcom) cards. So you will need to check as installing the incorrect driver can harm your system