All versions of Windows make use of a swap file. This is virtual memory and acts as hard drive storage space for memory items when you run low on actual physical memory. Use of the swap file slows down Windows quite a bit because hard drives are simply nowhere near as fast as system memory. But, you can speed up access to the swap file by using stripping. Stripping is a technique of RAID whereby data is spanned across more than one drive at the same time. Windows XP has code built-in which will stripe the swap file across two drives when you assign sizes to more than one partition. In order to take advantage of this, you need to have two or more hard drives in your system and place the swap file across the two separate drives, not simply two separate partitions on the same drive.
Go to Control Panel > System > Advanced > Performance / Settings. Hit the Advanced tab and go down to the virtual memory section and hit Change. Choose your first partition where you want the swap file, then select Custom Size and enter the size you want. If you set the initial size and max size to the same value, the swap will not be resized on the fly and can lead to better performance. Then choose another partition on a separate drive and do the same.
Windows will then split the swap file among the two drives.