When you do get online, are you doing so from behind a broadband router? Or do you just go right from the cable or DSL model right into your laptop?
Can I assume correctly that your light shows aren't super complex and complicated?
Is your XP 32-bit or 64-bit? I'm willing to bet 32-bit, it's much more common.
Your specs seem fine. HD is a little bit small, but for a fixed application computer, it's more than enough.
Were you running on batteries or via AC? What are your power saving settings or did you totally disable those?