There's not a single correlation between the machine you run to maintain the site, the machine the web-hoster runs to house the site, and the machines the whole world uses to view the sites (with IE, Firefox, Opera or Safari). Most web-servers run Unix or Linux, in fact, some Windows NT. You'll only know the difference if the links on the site are case-sensitive, then it's Unix or Linux!). I can't imagine anybody running a webserver on a Mac, but - apparently - they do exist.
You'd better look for a ISP that actively discourages and monitors sending spam. Read through http://reviews.cnet.com/5208-6122-0.html?forumID=44&threadID=104469&messageID=1196104 to see they do exist.
In the meantime, of course, there's no need to send (and possibly) receive your mail via the same provider that hosts your website. Nothing wrong with any other provider, I should say, although I'm inclined to say I wouldn't take email@example.com very serious. But firstname.lastname@example.org (or whatever your provider is) would not be worse than email@example.com for a new business, I think (I intentionally misspelled the possible address to save you spam if it should exist).
I really can't give any recommendation for hosting. Maybe try the 'small business' forum?
I tried to find the right host for my new business' website, and saw that iPowerWeb were Mac users. I was happy with the prices, etc, but now I can't send email because there is all kinds of spam being reported from my web server's IP address. The company is supposedly trying to 'fix' the problem, but in the meantime, 'spam cop' and AOL and Yahoo are bouncing my emails. Maybe it's a virus on the server, but I thought they used Macs? Anyway, does anyone have recommendations on dealing with this, or finding a better host, or any tales to share? Thanks in advance for your help!