[danielki]

Yes and no. There is at least one case that I can remember[0] of pirated software being modified to download and install a virus.

According to Microsoft[1], 32% of pirated Windows 7 copies and activation cracks resulted in some sort of malware infection

Speaking anecdotally, most of the friends and family whose computers I've had to clean up have been running some sort of cracked/pirated software that they'd downloaded or had been given to them by a friend

[0] http://voices.washingtonpost.com/securityfix/2009/05/pirated...

[1] Admittedly, Microsoft has somewhat of a bias, but the number sounds reasonable to me: http://archive.news.softpedia.com/news/32-of-Pirated-Windows...