Hello again;
Sorry for the confusion. What you must do is boot from the Windows XP CD (yes, you may use the Home CD to repair the Pro installation with CHKDSK /R, but not to run a full repair installation... I'd try to use or find a pro CD if possible to ensure compatibility if the CD copies files to replace corrupted files during the CHKDSK). To do this you must set your boot order to have your CD-ROM drives be the first devices booted (Generally keep tapping the: Delete Key, F1, F10, or F11 when you first power on the PC, it should have a note as to what to do for your PC / Motherboard brand in the bottom right corner of the screen). Once into the BIOS, generally the option is either under Standard Options, and Boot Order, or sometimes in other proprietary cases, you will have a Boot Order option right at the main screen. Set the CD-ROM device to be the first bootable device by using whatever the modify keys are (Generally +/-, F5/F6, Left/Right Arrows).
Once the CD-ROM is set as the first boot device, have the Windows XP CD in the drive when you turn on the machine; when the system attempts to boot it will read the CD-Drive before your hard-drive, and will say "Press Any Key To Boot From CD....", with continuing dots, press enter/spacebar or whatever at this time to boot from the Windows CD. You will watch a blue screen copy files into RAM ect.. for about two minutes, and once finished be prompted as to:
Continue by pressing enter (Do not do this)
Repair using Recovery Console by pressing "R" (do this)
Quit by pressing F3 (Do not do this)
Once you press R, follow the instructions from the previous post. As JonIsGinger says; it's always wise to back up the files you need before performing any of these tasks (normally not due to files being erased by chkdsk /r or repairs, but due to the user making an error, and formatting their drive...) Mind you all of these steps are only if you absolutely need the data on that drive; if you need no data off that drive you can just format and reload using the Gateway Recovery CD's (test your hard-drive first please, because this may be the source of the problem, and if it is it will seem to work for a while, then do this same thing over again).
If you cannot figure this all out, and I am getting to technical (ie: you have no idea what a "BIOS" is), I would recommend just taking the PC into the local shop (unfortunately for you, this is a Best Buy... ughh), ask them NOT TO TOUCH THE OLD HARD-DRIVE, and to install a new hard-drive, perform the Gateway Recovery / Reinstall on the new drive, and to hook up the old drive as a slave drive so you can access all your old data on drive D: when you get the PC back. The approximate breakdown of the costs should be as follows (by my standards anyways):
Format / Reload + Install HDD, XP, Drivers, Updates (or run recovery disks): $95-125 (Canadian Dollars)
New Hard-drive (If Needed): $40-100 (Depends on size)
The reason I said to put a new hard-drive in opposed to troubleshooting the issue with your drive, and backing up the data is that the new drive is normally less expensive then diagnosing a problem with your hard-drive, and backing up your data...
If you have any other questions, post back.
Good luck, and God Speed!