Short of installing Linux, and I run Linux and have as my main OS for more than a decade, you should consider:
1. If you computer has been compromised, you should back up your data to a USB drive and scan the shit out of that, and pave your computer. (Re-install the vendor backup of the OS). Then download some combination of the things in the following steps to that USB disk while keeping your computer off the net.
OK, that takes effort, so you probably won't do that. But if you do the above, or you don't, I'D VERY STRONGLY SUGGEST:
1. Download a decent firewall. Bothe Zone Alarm and Comodo have basic firewall products that are free for home users. Pick one.
2. Download a good free virus scanner. Both AVG and Avast have good free basic firewalls for personal use. Pick one.
3. Grab a good malware removal program. One has been mentioned that I don't know much about, BUT I'D SUGGEST BOTH CCleaner (Which has other good tools) and Spybot Search & Destroy.
4. Ditch IE. Really. Pick Firefox, Safari, Chrome, or Opera in roughly that order, IMHO.
5. If you can try to swap out Outlook for Thunderbird, and Office for OpenOffice. YMMV.
6. Keep all of the above up to date, along with your OS, and run your malware scans regularly.
Paving your system is ugly, but you should never trust a compromised (or public) computer. Even if you don't pave, follow the latter steps. Oh, and as a last resort, you can pull the drive in the Windows machine and either slot it into a USB case or another computer, and pave it, scan it, or fetch your data. That has some risk to the computer in question, and under no circumstances should you try to run, load, or preview anything from that drive. Another soultion would be to find a bootable CD / DVD / Disk / Whatever that has a good virus / malware remover on it. Boot that then scan the drive.
Personally, if I like you (not you specifically) I'll salvage your data, AND I always just pave the system, and install the above listed software on it, and do the updates. I've done that for friends and in a professional (LOL) capacity. That's basically what any sane IT department does when confronted with a compromised or otherwise fucked up Windows box, except they'll usually have pre-made disk image they can barf back onto the box while expecting you to have your files on a network drive. (Preferably on some daily backed up *NIX box with a decent RAID setup, as opposed to, gah, a Windows server.)