Mac or pc for photography work

Old hardware does not equal obsolete. That's just what the marketing people want you to think so that you upgrade your machine every couple of years.

Not being able to use new software because there's a new operating system that's completely incompatible equals going obsolete.
[URL="http://www.google.co.uk/url?sa=X&start=1&oi=define&ei=bKezSODZJY-Q0QTmyuWBBw&sig2=LH_YVU6uyQ9SSjzQ58xeuw&q=http://en.wikipedia.org/wiki/Obsolete&usg=AFQjCNG3P2arr_oLPqr1gl0lb5A2CHa94Q"][/URL]

Old hardware that cannot cope with modern software that you need to run equal obsolete.