i've been reading many websites about xp tweaks, some say you should tweak while others say it's a waste of time. in particular the paging executive, should it be disabled or not?? also the large system cache.....on, off?? the IRQ8Priority tweak?? i'm confused.

If you are happy with the way XP is running for you, forget about tweaking. It can break the OS unless you know what you are doing. i_XpUser

Disable Paging Executive Note: Only users with a large amount of RAM (256MB+) should use this setting. By default, XP pages sections from RAM memory to the hard drive. You can easily keep this happening and keep the data in RAM, resulting in improved performance. Optimize the System Cache Size (Windows NT/2000/XP) This setting controls whether the system cache is optimized for a Desktop computer or network server. Network servers usually require more memory dedicated to file caching, while desktop computers require more memory for running software applications. From arstechnica.com: On NT Server (in this case XP), the Large System Cache option is enabled, but disabled on Workstation. The two different settings effect how the cache manager allocates free memory. If the Large Cache option is on, the manager marks all the free memory, which isn't being used by the system and/or applications, as freely available for disk caching. On the flip-side (with a small cache), the manager instead only sets aside 4MB of memory for disk caching in an attempt to accelerate the launch of applications. Or in a more technical approach, if enabled the system will favor system-cache working sets over process working sets (with a working set basically being the memory used by components of a process). Force IRQ Priority This is a tweak that falls into the category of imperceptible, but some may find it useful if a hardware device is being a bit of a laggard. This tweak can be applied to multiple IRQs and the best use you could make of it is to try to improve the performance of devices that share an IRQ over non-shared IRQs. The effect of this change is to improve the performance of devices on the nominated IRQ. It is often used to boost the performance of the System CMOS/real time clock, normally residing on IRQ8.