a mountain of processes

Hello all, just got a new compy the other day and am having a problem with it getting bogged down with processes. It works fine for a while and then begins to fill up and eventually the cpu usage shoots to 100% and I have to manually restart because of it. There will also be about 10 of the task manager icons in the tray at this point. My question is, can I find a place that has a list of legitimate processes that I can compare mine against? Is this possibly a spyware or virus problem? My OS is xp professional, thanks for the advice in advance.

All the processes that, under user name in the task manager, are reported as SYSTEM are processes belonging to windows and are often critical. Then i have alg.exe as local service and two svchost.exe processes as network service.

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