In the UK, windows is used WAY more than Mac. I personally prefer using a Mac, and I have both iWork09 as well as OpenOffice.org [for companies who use either windows or macs but if i work in pages or numbers then i can always save in .doc/.pdf
for designing, well... I use GIMP which is free for making pictures/logos/designing; and for websites I use a template that I find online and customize it in Bean [a html editor for mac]
I have to say that, in the UK it is really up to you. I'm pretty much a MAC convert now, but for you americans, I guess that you are really used to having people using MACs frequently. However, as my niche markets are musicians, TV/Radio and graphic designers, it's more advantaged on my half that I do use a Mac [albeit most programs being used are free for the moment!
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