I'm taking your word this is just XP. As such I'd get it updated and hope that XP SP3 works without having to do more research.
When you do your research I find this phrase to find prior discussions on this.
"How do I use a bluetooth headset with windows XP and Skype?"
I have connected a Bluetooth USB Dongle to my pc that is using Windows XP. I have been able to pair my LG 730 headset to the computer but in property's / services there is nothing listed. I am assuming that in order to use the lg headset as my seekers they would need to be listed. I have also checked in the sound and audio property's and there is nothing listed other than my desktop speakers in default devises.