My PC is all up to date with updates& patches etc and I have all the security software to keep it protected it's just a matter of it slowing down my PC.

I have the following installed to do various jobs works fine but do I really need it alll and if not what can I take off?

Tuneup Uttilities 2008
Spyware Doctor 5.5
Registry Maestro 7
ZoneAlarm Security Suite 7

I also noticed when I upgraded Microsoft Office 2003 to 2007 It did slow down

Thanks