Can someone please explain about the registry cleaners that keep popping up. What is it and why get it?

normally when an application download is popping up on your screen its a clear sign of an infection…
step one DO NOT CLICK ON THIS it will only further harm your computer.
now go get super antispyware (superantispyware.com) and run it, it should remove it… if it doesnt .. follow below directions STEP BY STEP !!!
get these free tools… adaware(lavasoft.com) spybot(safer-networking.org) HiJackThis(trend.com) winsockfix v1.2(majorgeeks.com) CCleaner (ccleaner.com)
install and run the adaware/spybot updater
disable restore
start-run-apps-accessories-sys… disk cleanup
reboot safe mode w/ networking (continually press f8 upon reboot)
Run adaware and spybot deleting anything they find.
Run Hijackthis (this shows all BHO’s on ur browser~very important)
Run CCleaner (Repair/delete anything it finds)
Run free online scan (trend.com bitdefender.com pandasoftware.com) remove any findings
Run winsockfix v1.2
reboot
enable restore

you might also try these commands in your run box
start run cmd ~
ipconfig /release
ipconfig /flushdns
ipconfig /renew
netsh int ip reset
regsvr32 softpub.dll
netsh int ip reset resetlog.txt
netsh winsock reset catalog
netsh interface ip delete arpcache

please note ::: using mozilla firefox with the following addons noscript noflash adblock (95% reduction in spyware/malware)