It's wise to collect configuration information on your hardware before installing. Know the vendor and model number of each card in your machine; collect the IRQs and DMA channel numbers. You probably won't need this information -- but if it turns out you do, you'll need it very badly.
If you want to run a "dual-boot" system (Linux and DOS or Windows or both), rearrange (repartition) your disk to make room for Linux. If you're wise, you'll back up everything first!
If you have an EIDE/ATAPI CDROM (normal these days), check your machine's BIOS settings to see if it has the capability to boot from CD-ROM. Most machines made after mid-1997 can do this.
If yours is among them, change the settings so that the CD-ROM is checked first. This is often in a 'BIOS FEATURES' submenu of the BIOS configuration menus.
Then insert the installation CD-ROM. Reboot. You're started.
If you have a SCSI CDROM you can often still boot from it, but it gets a little more motherboard/BIOS dependent. Those who know enough to spend the extra dollars on a SCSI CDROM drive probably know enough to figure it out.
Here are the basic parts of an installable distribution:
The issue here is that some hardware drivers conflict with each other in strange ways, and instead of attempting to debug hardware problems on your system it's easier to use a boot floppy image with only the drivers you need enabled. (This will have the nice side effect of making your kernel smaller.)
You only need RAWRITE.EXE if you plan to create your boot and root floppies from an MS-DOS system. If you have access to a UNIX workstation with a floppy drive instead, you can create the floppies from there, using the `dd' command, or possibly a vendor-provided build script. See the man page for dd(1) and ask your local UNIX gurus for assistance.