Memory management - Windows XP 32bit

Hi, I've got a quite annoying problem with my 24/7 running system, which is set up like this:
- Motherboard: Asus M2NPV-VM
- Chipset: nVIDIA GeForce 6150, AMD Hammer
- CPU: DualCore AMD Athlon X2 BE-2350, 2100 MHz (10.5 x 200)
- RAM: 2x 1GB Corsair XMS2 CM2X1024-6400C4 @ 350Mhz 4-4-4-12
- HD's: SAMSUNG 400GB, SATA II + WD 500GB, IDE

The system is used for office tasks, ripping and as a mediacenter and fileserver.
Now, here's the question: when I copy large amounts of data from this system to another (gaming rig or laptop, both running XP aswell), the system becomes unusable during the taks of copying. It takes for example about half a minute to maximize Outlook out of the traybar and when I'm listening to music, there are "skips" noticable in the tracks. The funny thing is that any monitoring tool shows me at least 1GB of free memory, CPU usage beeing never over 20%.
Does anybody know how to solve this problem? Is it the (very) bad memory management of Win XP? Is there a workaround? Would the use of a Linux distr. for the 24/7 machine be a better choice?
Thanks for any advices and suggestions.

wow, all most sounds like a bad install of windows or bad memory. ive never had that problem with my XP 32-bit and im running the latest patches and everything.