You don’t give enought info. but at general, you SHOULD do these:
1. Apply most Microsoft recently patchs
2. Keep your virus definitions up to date (you have an Antivirus, right?)
3. Minimize services (shutdown all you’re currently don’t need)
4. Try to keep your website organized, with folders, and put each kind of files (images, apps, html) at each folder. Give the correct NTFS permissions to ’em
5. Finally, If the “data” on your servers is more important than the real efforts you’re doin’ (can), get a external consultant and let him probe/test your network.