Antivirus 2008 with vista?

Hey guys yesterday i was unlucky and got antivirus 2008.My computer went nuts and i got pop ups saying i had this trojan and that and advertisments for software to download and buy.The my windows defender turned off saying it done so because my computer was not safe.Then i got a message saying Notebook doesnt work no more.I checked a few sites and purchased Spyhunter for $30 and that got rid of 8 trojans and numerous cookies.Then when i logged onto the internet i get bombarded with the same stuff as yesterday,i cant click any link because it redirects me to different sites,every single time.I cant download anything,it wont let me do a system restore.I downloaded Smitfraudfix and that would not run,i get messages saying access denied.When i open my gmail account i have a red logo saying my computer needs to fix a serious prblem to prevent corruption.I have found some dll files and googled them,they are viruses but cant delete them,anyone got any ideas what to do next?all help welcome...