Slow PC and dialog box on boot up

I have recently fitted a new video card to a PC which restored the monitor display. However the PC is now slower than it was and on boot up 3 dialog boxes are displayed: ‘Install X: File not found: C:\windows\installx.inx’; then ‘Install X: There was an error installing the application file (Error 101)’; and finally ‘Installation failed’. How can I speed the PC up and get rid of this annoying message? Is the message referring to the old video card which is still listed in Device Manager? How can I remove the old card from Device Manager, would this be a case of changing jumper settings and if so how could this be done without the manual? Memory on the PC is fine.