I downloaded a windows xp service pack 2 then the computer had to shut down to run the program but when I tried to re start my computer it won't let me it restarts up to the blue screen then starts to reboot again I've tried all the options on the F8 button. I can't get into the computer to reinstal anything?? :confused:

I always use the XP Service Pak 2 disc I got from Microsoft. Anytime I tried to download the update my computer went nutty just like yours did and I had to start from scratch all over again. I think Microsoft still sells the disc but you'll have to pay about $10 for it. It used to be free and free shipping but that stopped happening about 4 years or so ago.

What is the error number on the blue screen?
Try booting the computer with a boot floppy. You can manually make one (How to create a bootable floppy disk for an NTFS or FAT partition in Windows XP (http://support.microsoft.com/kb/305595)) or download image from Bootdisk.Com (http://www.bootdisk.com)

If the filesystem is Fat32, you may even boot with a Win98 boot floppy.
Once at the command prompt A:>
Type this:
Cd $ntservicepackuninstall$\spuninst (press ENTER)

Type:
Batch spuninst.txt (press ENTER)

If you have a Windows XP CD, boot with the CD in drive (you may have to press a key to boot from CD); also you may have to change the options in your computer BIOS (setup) to list the CDROM as the first boot choice.
The CD will go through the motions as if you will be installing Windows. Once done loading its files, at the screen where it asks you what to do, choose R for the Recovery Console. You may have to enter a password (if you have one set , which you should). Once at the command prompt, type the same as mentioned above.

Note: if using the second method (booting with the Windows installation CD) and going into Recovery console--->after the last statement 'batch... ', after pressing enter, type EXIT at the prompt.

Once back into windows, to actually uninstall SP2,
Click Start, go up to Run, type CMD in the test box that opens.

At the prompt (>) type this:

Cd\
Cd %Windir%\$NtServicePackUninstall$\Spuninst (press enter)
Spuninst.exe (press enter)

I would suggest a repair installation
Repair Installation
A Repair Install will replace the system files with the files on the XP CD used for the Repair Install. It will leave your applications and settings intact, but Windows updates will need to be reapplied.

Perform a Repair Installation (http://www.microsoft.com/windowsxp/using/helpandsupport/learnmore/tips/doug92.mspx)

I would suggest your going to Win XP SP3.

By chance is this a legal copy of Windows. I'm not accusing just curious.

Rick