hard drive not booting:DRIVER_IRQL_NOT LESS OR EQUAL

i got a new graphics card today(ati 9800xt) & installed it & downloaded the drivers etc. i then tried to put a hard drive i got out an old computer(2.1gb western digital caviar 12100 ata. when i tried to but with the 2.1gb & my 250gb samsung sp2504c sata(what i have everything stored on). it tried to boot up windows 98(on 2.1gb hdd) even though i wanted xp(on the 250gb). i then recieved an error message:cannot find device file. the windows registry or system.ini file refers to this device file, but no longer exists. c:\progra~1\norton~1\savrt.vxd i took the 2.1gb out & tried to boot as normal using the 250gb, but it just wouldnt boot. i tried everything, when i tried safe mode, it said: DRIVER_IRQL_NOT LESS OR EQUAL no matter what i done i couldnt get it. i ended up putting windows xp onto the 2.1gb hdd & it eventually recognized the 2 of them. does anyone know what these errors are? & is there a way i can get my 250 running the way it was? i was thinking i could maybe transfer the file or whatever is missing from the 2.1gb to the 250gb, but wouldnt know how to do it.... can i still play games that are in my 250gb hdd?? if so, how?? i want to use the 250gb as the master but isnt booting up?? what can i do? I WOULDREALLY APPRECIATE SOME HELP AS IVE TRIED EVERYTHING I CAN THINK OF SINCE IT HAPPENED(10 o'clock this morning). THANK YOU VERY MUCH FOR TAKING THE TIME TO READ THIS & HOPEFULLY YOUR HELP:-(