Love Linux /But need Windows: Dual-Boot

To install Linux on a Windows PC, you need to create a second OS partition to make room for it. If you have a factory-installed version of Windows on your PC, chances are it uses the whole hard disk as a single partition. So if you have a hard drive that is 40 GB, this means that your PC with the 40GB hard disk, has a C:\ drive that is roughly 40GB in size.

You can use a commercial partitioning utility like Symantec's Norton Partition Magic 8.0 to resize partitions without affecting partition contents (though it's always a good idea to back up the contents first). If you don't want to spend $70 to be able to resize partitions just once, you can use McLaughlin's free Partition Logic utility. This is a downloadable boot disk image that you burn to CD, and then use to boot the PC and create or resize disk partitions.

A typical Linux desktop installation requires somewhere between 2GB and 3GB of disk space these days, but can take up even more room if you select lots of the optional programs on the install discs. Give yourself about 8 or 9GB for Linux.
The default file system in Windows XP and Windows 2000 is NTFS, a system Linux knows how to read, but cannot write to. And no version of Windows can read or write to the Linux file system partitions. All this means that there's no easy way to work on documents in one OS, then boot to the other OS and continue working on the same files.
Best thing to do is make a FAT 32 Partition. Windows XP will support the older FAT32 system, that lacks NTFS's (FAT 64) security features and is therefore readable and writable from Linux. Give yourself about 10GB FAT32 Partition.

When you install an operating system on your PC's hard disk, the process usually puts a small program called a boot loader in a reserved hard disk location called the master boot record. When the PC powers up, it launches the boot loader program stored in the master boot record, which in turn loads the operating system or offers a menu of operating system choices. After you install Linux on your Windows system, the Linux boot loader (these days, most distributions use GRUB, the GNU GRand Unix Bootloader) replaces the Windows NTLDR boot loader.

Note: if you reinstall Windows (because you're upgrading, or recovering from an incurable spyware infestation, for example), it will overwrite the Linux bootloader with NTLDR, removing the option to boot to Linux. To restore the Linux boot loader, boot the PC with a Linux installation disc and select its rescue mode. There, you can use the command-line version of the GRUB boot loader to detect the Linux partition and restore GRUB to the hard disk's master boot record, where it will be located in most dual-boot configurations.