I came across this while browsing Microsoft and thought it was worth posting... (Updated, thanks guys for pointing out some errors!!! Ed.)
When you use the Microsoft Windows XP device drivers for the Creative SoundBlaster Live! audio adapter, a memory leak can occur. This can cause the computer to lose system resources and run more slowly.
This problem occurs with the SoundBlaster Live! device driver that is included with Windows XP.
A supported fix is now available from Microsoft, but it is only intended to correct the problem described in this article and should be applied only to systems experiencing this specific problem. This fix may receive additional testing at a later time, to further ensure product quality. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Windows XP service pack that contains this fix.
To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, please go to the following address on the World Wide Web: https://support.microsoft.com/directory/overview.asp
29-Aug-2001 15:58 5.1.2600.10 132,864 Portcls.sys
There is actually an update for the Live! cards on the WindowsUpdate site for the Creative SB Live! (WDM) - V. 5.1.2601.0.
But it looks like the file, Portcls.sys does not seem to be included! Looks like Microsoft are holding this update until SP1 for XP! (Come on Microsoft, release the fix, Ed.)
On another note, I did notice the existance of a new keyword :- "kbWinXPpreSP1fix", oh goodie!