Change the one which says PIO to DMA If Available, then reboot.
If it's still saying PIO for Current Mode then see here for info on how to edit the registry to reset everything:
Unless the drive is really old (like pre 1998 or something) then all modern drives support DMA/uDMA Mode. No drives should be running in PIO Mode under WinXP.
When a drive goes into PIO mode it's probably a sign of faulty hardware or imminent failure (eg. a drive will start in uDMA Mode 4/5/6, but after each critical error it'll reduce in increments of 1, until after another error in uDMA Mode 1 where it'll then go down to PIO mode).
To find out which drives are located where (Primary or Secondary IDE Channel, Device 0 or 1) either open up the case and look, or enter the BIOS on bootup (Standard CMOS Features section). Sure there's probably Windows apps/tools out there which you can use, but that's the way I've always done it, heh.
Generally though, if either the CD-ROM Drive (usually but not always: Secondary IDE Channel, Device 0) or Hard Drive where Windows is located (usually: Primary IDE Channel, Device 0, C: Drive) is running in PIO mode then that's bound to be the cause of choppy CD playback (amongst other general slowness issues).
One thing's for sure though is it's not a Winamp problem, and certainly not a 5.25-beta-specific issue. That I can gurarantee.
the above was just an example, and not based on your particular system/settings