Downloads Blocked and Browser Hijacked

Help!! My browser/search engine has been hijacked qnd I can't download anything! - whenever I bring up Internet Explorer and google for something Simpli.com comes up. So I was reading on this forum about how to disable it so I tried to download Spybot and AdAware and now I can't download anything! It seems my hijacked browser is not allowing downloads, I just get a quick flash and view of green progress timer at the bottom. I finally just went and purchased Professional edition of AdAware so I get a CD sent to me (has not arrived). The folks at Spybot were nice enough to send me their program via email - I unzipped it and it won't run! Giving me message "CoolWWWSearch.SmartKiller (v1/v2) has not been found on your system. I am at my wits end. Has anybody experienced this or have any ideas? I have run Housecall and Norton AntiVirus successfully. I just want to get some Spyware removal software installed and get rid of Simpli.com. Regards, DC