Screw antivirus software. First, go to another computer that you know is secure (a well-maintained public machine - like at the library - works, or the computer of a tech-savvy and cautious friend) and change all of the passwords for your internet-related stuff. Backup all of your important documents - anything that isn't a program. Backup all of your scripted stuff (Flash documents, MS Office files) to a different disk so that you can check them for macro viruses later. Then wipe your computer - find a disk utility that will actually overwrite your whole hard drive with blank data. Your hosting company has probably already done so, but if they have any of the old data from your site, you should remove it all (preferably just delete it, or if some things are irreplaceable put it on a disk to pick through later.) Contacting your bank(s) as the others said is also a pretty good idea. You might also want to call anyone that you make regular online payments to, such as your utility companies - those folks do have a fair amount of your sensitive information, and they aren't always the best about keeping it private.
Particularly if you're doing something like running a website, where you disseminate data to thousands of other users, you should have your computer set up so that you can do the above stuff at any time with little trouble. Adopt a filing method that will allow you to find all of the stuff you need to keep without a lot of searching - this will make backing up and rebuilding faster. I suggest getting a second hard drive to be used exclusively for maintaining backups of any files you create or work with before posting them online, so if anything is ever compromised you have your data in a separate place from your system and configuration files (which is where things usually go wrong.) Then all you need to do is disconnect your backup drive and you're ready to wipe the rest of the system down. When you go back to reconnect it, since you only used it to save your documents and static files, you'll know that if any programs start running from it, they're not supposed to be there and can be removed. You could also consider finding yourself a cheap junker computer to use for your day-to-day casual internet tasks.
The benefit to any of these options is that you can re-install your operating system easily once you come up with a routine for doing it. It is a chore, but for most users you can actually get a pretty noticeable performance bump if you do it, so it's not just something for treating urgent problems like viruses. It shouldn't be necessary, but most operating systems tend to accumulate unnecessary and erroneous configuration data over time - files are loaded at startup to support programs you deleted long ago, or bad data gets saved in a setup file and has to be corrected each time a program loads because no-one thought to overwrite the setup file after the information was fixed. I work tech support at my school and am also going for a degree in computer science. The kinds of problems we see with software most of the time are truly asinine - it never ceases to disappoint me.
Best luck...
~Joe
PS - When I first saw this thread I thought that "attack site status" was some sort of honor among the internet metal communities or something. CONGRATULATIONS!