besyaf.sys - Corrupt missing after virus attack

I have a compaq presario cq70 running vista updated with most recent updates.

Recently Avira alerted that a trojan was attempting to gain access to the computer and gave the options to "delete, deny, quarantine etc" I selected delete and it kept on popping up so i kept on selecting delete. Then did a full scan using superspyware, spybot, (all the ones recommended here in the "Virus removal thread")

Then i got the Blue screen of death (which i didnt think existed in Vista)

Now when i try to start the PC it fails and says

File: Windows\system32\drivers\besyaf.sys (0xc0000098) critical driver missing.

I do not have a recovery disk as its a HP machine and they never gave one.

Can you download a bootup file to an ipod or sd card?


Thanks for any help.

 

Update: I managed to do a restore of windows vista from using the partition. Everything seemed fine so i installed the latest Avast. During the creation of a restore point I got the blue screen again. After a computer restart avast was running and up popped an avast warning about my old friend besyaf.. "rootkit detected - infected file besyaf - options delete/ignore" I didnt delete as i would be back to square one. Im in the process of running the "READ ME - VIRUS REMOVAL etc"