Windows XP Service Pack 3 Got Real Slow

Hello,
My notebook gets really slow when I run some exe files. It has 2 GB RAM and 2.00GHz Processor. Processor and RAM Usage is less than Half. One thing is for sure that its not due to viruses. What I fell is that it may be after installation of one of the two softwares
1- Siemens PCS 7
2-Copy Handler

Kindly help me in this regard. Also note that I have disabled indexing services but it proved useless