XP is secure, and in general the best OS that MS has to offer.
ARe you sure you have no task manager - is there ANYTHING that comes up - perhaps a GREEN statistics box with a grey "border" (window). If so, double click the top of the "grey border".
You tabs will appear.
If you don't have this, then it could be due to security restrictions, but I presume that you are really the top user.
XP is pretty reliable. If there is ever a problem with any XP machines I have looked at, it is always the HARDWARE which is faulty, or the installed DRIVERS that are incorrect.
There are better OS's out there (Linux - based on UNIX which is far superior), but they can have the same problems - hardware faults or incorrect drivers.
But, providing that your hardware is good (just coz its new, doesn't mean its good or stable), and all the correct drivers are installed, then if you are having problems it is likely to be spyware - or a virus...