Keep getting checkpoint errors, and have changed Sys Battery , reset Bios and when i boot it ,it goes to Dell logo and keeps trying to reboot. Windows will not load.

Try going to the BIOS and see if it reboots from there. If it does, then it is most probably a hardware problem. You can try re-seating the memory modules and If you have multiple modules, try them one at a time.
If it does not reboot while you are in the BIOS, then the problem lies on Windows. Get your DELL Restore CD or your Operating System CD and insert it to the CD-ROM drive. Reboot the computer and press F12 while seeing the Dell logo, that should give you the options to boot to CD-ROM. It will give you a quick prompt of "press any key to boot to cd..". Make sure you press the space bar during this time to initiate the boot from CD-ROM.
Once the Windows Setup loads, Choose "Recovery Console" to repair your computer. Just choose the installation you would like to repair (normally it's number 1) then it will ask you for the administrator password. By default, the password is blank, but if you set a password for admin then use that password.
Once you get to the prompt, Type this command. "CHKDSK /R" (without the quotes). It will initiate the repair for your OS. This might take an hour or so. Just wait for it to finish and it will automatically reboot your computer. Let the computer computer reboot normally. You should be able to get to your normal windows screen back.
Good Luck.