Oracle 11g R1 WinXP SP2 CPU 100 percent all the time

Hello I've installed Oracle trial/demo EE software (Oracle site) Win XP SP2 computer 2 gigabyte storage without applying any rotten tricks. (Easy and basic installation, no pre installation warnings, nothing!). Administrator of WinXP is in the ora_dba group, allow batch and so on is set, dba_group +