Is there any way to fix this computer problem ourselves?

Our computer is several years old. The other day I updated the Norton Antivirus software which is part of the Constant Guard program we get free from Comcast. The computer had been funky before that (slow, crashing often, etc), but when I tried to restart it after the update it got stuck on the “Windows is starting” screen. After a long while, I turned the computer off, waited, and turned it back on. It worked for a while, then froze up. When I again tried to restart it, it got to the “Windows is starting” screen and stayed there.

Is there any way to fix this? We plan on getting a new computer (luckily we have a laptop so we aren’t totally cut off from the world, haha) soon, but we’d like to be able to save some of the data so we can transfer it to the new computer. Will we need a professional at this point? Anything to get it up and running for at least a while would be extremely helpful.

I think it has Windows XP but I’m not 100% sure on that. It’s a Dell computer if that makes any difference.

Thanks!