PCs are apples, and Suns are oranges, and I like oranges better.
Seriously, I would not use a Sun for PC tasks, and I would not use a PC for a Sun task.
PCs you can configure, run pretty office software, good for playing games, can be administrated by someone w/o a BSCE or a lot of time on their hand.
Suns are powerful for certain tasks, like huge databases and servers, well configured and supported, and you pay a premium for them.