Persistent virus follows after formatting

Yesterday night I was installing a program and it made my computer vulnerable/ attracted viruses. My computer got viruses, im not sure how many but there were two very visible ones. One of them hijacked my desktop and changed it to a black screen with a message saying "your computer is infected with viruses and stuff" and another was a anti-virus scanner doing a scan. In addition, the viruses prevented me from opening any programs and disabled regedit and my system restore (im not sure if thats all they disabled). whenever I opened a program there would be a error message at bottom right saying "that file is infected and cannot be opened." However, I was able to access malaware and superspyware free edition in safe mode and did a scan for all viruses, etc. on my drives before i formatted. After I formatted, 20ish minutes after I was connected to the internet and installing programs i suffered the exact same viruses and symptoms as before. what first happens is a install prompt appears asking if i want to install some program (can't remember the name of it). then 4 files appears on a drive (i was able to delete them though) and then all hell breaks loose and the bigger viruses come in. I am then unable to do anything because of the infected files stopping me from opening programs. Now i reformatted again, my internet is disconnected, I am running super spyaware free edition and malaware scans over my entire harddrives and planning to install smitfraud and adaware after the scans are finished to do another scan. Is there anything else I can do to ensure that my computer will not get infected again? Perhaps theres a really good antivirus program that has a trial (i used bitdefender and kaspersky's trial already)Atm, the scans are picking up nothing, if so how did i get infected by a virus?? thx for reading this.