my laptop computers locked up due to old operating systems

I can not believe what I did.  One of the laptops had windows xp the other has windows 2000 but when it backed out I got a new monitor and reinstalled the windows 2000 operating systems and utitlites from the other model.   Now I am stuck even trying to get plugins & add ons from modzilla and/ or service paks and adobe flash programs for Internet Explorer stuck at 6.00 keep  with errors. Can that be fixed.?

from crusaders 82:  Also, someone posed that I could combine RAM from my two Latitude C510/610 laptops?    Would it be connecting two  ports at the back?  I also have a 8 GB Flash Drive I never used.  Can this help install and run a critical program?  Thanks for helping.