Pop-Up Scams, Rogues and Scareware
Pop-Up scams take the form of windows that pop open when you visit a website that appear to be alerting the visitor to a potential computer problem, such as a virus detection or corruption.
Often they use scare tactics to coax the visitor into downloading some software that they say, will fix the problem (that isn't there in the first place)
Be very wary of anything like this, as it will always be a scam.
Once their software is downloaded on to your computer, it will install all manner of malware and viruses, and more often than not, render your machine inoperable unless (through extortion) you pay them a huge amount of money to fix your machine.
Basically, any software that installs itself on your computer without your request, is almost certainly bad.
A simple online search using Google, or Yahoo for example, will often bring up all the information you'll need to decide whether the software in question is legitimate or not. Remember, be suspicious, and research the programs you install before you install them.
Here's a list of some of the many rogue applications doing the rounds:
XP AntiSpyware 2010
SecurityEssentials 2010 (not to be confused with the legitimate Microsoft Security Essentials)
SecurePcAV (clone of WiniGuard)
AdvanceDefender (clone of Personal Guard 2009)
PaladinAntivirus (clone of Protection System)
SafePcAV (clone of WiniGuard)
MyPCSecure & PcsSecure (clone of WiniGuard)
PCSecureNet (clone of WiniGuard)
LiveEnterpriseSuite (clone of InternetAntivirusPro)
GhostAntivirus (clone of InternetAntivirusPro)
APcSafe (clone of WiniGuard)
ProtectSoldier (clone of WiniGuard)
ArmorDefender (clone of WiniGuard)
DefendAPc (clone of WiniGuard)
SysDefenders (clone of WiniGuard)
InSysSecure (clone of WiniGuard)
SysProtector (clone of WiniGuard)
APcDefender (clone of WiniGuard)
PCprotectar (clone of WiniGuard)
PcsProtector (clone of WiniGuard)
GreatDefender (clone of WiniGuard)
Here's a recent list from Lavasoft