First of all I have been with dreamhost since they started before 97 they have the cheapest, best hosting and freedom of use policies I have seen in over 14 years of online mirc and other such environments. I would be willing to help you with the klez problem but a flaming newbie, I have no time for. In your own sign in you are new why trash someone who is providing an exceptionaly good service... take a look around the web and when you begin to write cgi, and html, vrml, and various other kinds of scripts as well as applets let me assure you dreamhost rocks. Now for the klez, first off McAfee is trash in my experience. Klez is not a virus but a worm designed to do exactly what you claim is happening to you. Not to mention modify itself each time it infects a machine. When you calm down and want help, let me know. Maybe if you ask nicely I may help. LOL But I doubt it. I really dislike flamers especially newbies who have no clue what they are talking about. Dreamhost nor any other isp can filter out this kind of attack. That's one reason I don't use verizon because I can't use dreamhosts mail because they don't allow hosted mail services. AT&T blocked port 80 for a long time because of trojans and viruses. I suggest you go to http://www.lockdown2000.com and read until you really know something. Then get norton's antivirus only, lockdown security suite and zonealarm pro running behind a router after you format your drive and reinstall. This would give you a sound software and hardware firewall. As well as, email attachment virus scanning. This would be a secure system. It seems to me, you can't afford, intellectually or financially to host a website. It seems you want Dreamhost to do it all for you. I would venture a guess that you use hacks and cracks on your software and probably use kaza or morpheus LOL these are well known for trojan and virus infection that is most of thier users intentions. I say practice what you preach grow up.
P.S. You should be aware that in your mail configurations, you can stop all attachments permanently.