Svchost Ssdp Discovery Service?

my xp sp1 athlon suddenly was stuck on startup with something causeing the busy pointer to never stop-i couldnt get into anything except by repeated ctrl/alt/delete to turn things off one by one-discovered it was svchost=ssdp discovery service?-disabled it from services and everything was fine again, but what was it doing there in the first place? i like to keep things at a minimum on my pc and try to turn off everything i can-went into add/remove windows components and saw a bunch of new things that were never there before-distributed transaction coordinator,wmi and com+ wont let me remove them? i'm just a home user not on any network, so i dont need/want any of the network tools/stuff.- i dont remember downloading or turning on anything new, but that doesnt mean i havent, if you know what i mean-awhile back, i did some tweak from kellys corner to add something to windows components, but i dont remember what it was now-if anyone knows what i did or whats going on, could you tell me how to turn it off again, or whatever suggestions there might be-i almost was getting ready to do an xp reload, as i hate when after awhile, you get all those extra undeleted temps, registry stuff, etc. that bog down your system-but if i can clear this up, i dont think i'm there yet