Windows XP doesn't use "resources" in the same manner as Windows 98/ME and therefore you won't find a "resource percentage" in a Performance area. The closest thing I can think of regarding that would be CPU usage which can be checked by opening the Task Manager (Ctrl-Alt-Delete), then click on the "Performance" tab.

Still, you can manage the number of start up programs and services in Windows XP in a similar manner as the previous operating systems. Follow the instructions in the link below to get that done:

How To Shut Down Unnecessary Start Up Programs

In addition, it's a good idea to clean out the junk files and run the Error Checking/Chkdsk program per the instructionss in the links below:

How To Clean Unwanted Files From The Hard Drive

How To Run 'Error Checking/Chkdsk' On Win2000/XP

Hope this helps.