0 connections now, but I had been using Bitcoin QT for a while without problems
By using process of elimination , I would do something like this.

First, I would reinstall your Bitcoin wallet and see if it works. If it works properly, there was probably a Bitcoind configuration file that was messed around with in your original installation or you were using an outdated version.

If it still doesn't work, install a Bitcoin wallet on another computer on your network and see if it works. If it works, than probably there was something wrong with the Windows configuration (maybe firewall or antivirus program is blocking access). If it doesn't work, there is something wrong with your network (may be problem in your router, or internet provider)

On a side note, I wouldn't recommend running a wallet on Windows XP if you plan to keep any Bitcoins on it, due to it being incredibly insecure since Windows stopped supporting it.