Install XP from a DOS Prompt as XP [b]Is Not[/b] a DOS Program so it's impossible to install from a DOS Prompt.
To get into Win 98 at the C:> Prompt type [b]Windows the pres Enter[/b] and that should open Windows 98 though if that installation wasn't for your hardware it's very unlikely to load as you will not have the correct drivers installed or available.
You can make a Bootable CD and boot off that or even use the XP CD to boot off and format the HDD with and then proceed to install XP simply by changing the Boot Order in BIOS from HDD 0 then CD/DVD ROM to CD/DVD ROM then HDD 0.
That way whenever a bootable CD is found in the Optical Drive it will ask you do you wish to boot off this and if it doesn't get a response within the allocated time it will default to the HDD to boot from.
With an XP CD inserted you'll be prompted to press any Key to Boot off the CD and then follow your nose with the relatively simple install procedure but first thing would be to copy your Product Key off the COA on the Case as they are not that easy to read when you are attempting to read them at an awkward angle with the light reflecting off it and making it very hard to read.
When you get to the option to format the HDD you should have 4 available options a Full & Quick Format Option for FAT32 and a Full & A Quick Option for NTFS use the Full NTFS Format option and then allow XP to install itself. You should only ever need to push any key once as once you start off the install process it will run automatically with you only needing to place your location Product Key and Time Zone into the Setup procedure. Not necessarily in that order though.
Col