Close all (browser) windows & rescan with hijackthis. When the scan is finished place a check in the box to the left of the following entries & click 'fix checked' :
R3 - Default URLSearchHook is missing
O2 - BHO: (no name) - {185FDDA7-A61F-89AA-1B04-DD423042EA06} - C:\PROGRA~1\MEETBA~1\debug new.dll
O2 - BHO: (no name) - {B4496A4E-1EE2-11D5-AC63-0010A4D17343} - C:\Program Files\Guru Inc\Shared\BHO.dll
O3 - Toolbar: Download site inter - {A5BA5867-BC9E-72B7-2A7A-8EF6C18733E6} - C:\PROGRA~1\MEETBA~1\debug new.dll
O4 - HKLM\..\Run: [System Service] C:\WINNT\System32\msrexe.exe
O4 - HKLM\..\Run: [UpdateSerialNumber] C:\WINNT\System32\updateserial.exe /s
Reboot into safe mode following the instructions here & navigate to & delete the following if found:
C:\WINNT\System32\msrexe.exe< file
C:\WINNT\System32\updateserial.exe< file
Reboot normally.
There are a few things there I haven't seen B4. Is this a work computer? If so & you know, can you highlight the entries that reference these work programs plz.
Update W2K to SP4 & also you should urgently upgrade to IE6 for security reasons. The one you use now is out of date & therefore very vulnerable to attack.