Check this out. The page is in Chinese but don't worry if you cannot read it, just watch the embedded video:
忘記 Windows NT 帳號密碼時如何登入
Kind of too funny. XD
Yes, Windows NT is so out-dated, but the fact is that there are still tons of large-scale organizations using such obsolete OS. Be aware man!
VirusTotal is a useful website for you to upload a suspicious files to check for viruses and malwares. It will use more than 30 anti-virus/malware engines to scan the uploaded files so it would be quite accurate, yet not 100%:
[quoted from the warning notice of the service]
Although the detection rate afforded by the use of multiple antivirus engines is far superior to that offered by just one product, these results DO NOT guarantee the harmlessness of a file.
Not only the service helps the users, but also helps the anti-virus/malware software vendor to collect the latest samples of viruses/malware. Unless the file contain sensitive or confidential information, I would recommend everyone to try this service out.