Themes - how important is it for your computer or mobiles?

There are too many themes i like for my Iphone and i'm always changing it. It can last me as short as an hour or as long as a week before i change again. Since there are constant updates to it, i have tons of choices to choose from and it's useless if i don't use them. I do have my favorites, but many of them appeal to me differently. When it comes to laptop themes, i have to be more professional about it since i'm using it for work, and nothing too cute.

I change the themes on my laptop once in a while. My PC is indispensable to me. I mean, I use it for work and social networking. It's almost using it at least half a day, everyday. So sometimes a change in theme helps me in part to avoid burnout from work. I usually use soft tones of color or relaxing scenery. Sometimes I put the picture of my kid to always remind me why I'm working very hard :)

I also use the simple look and my screen looks no different from win 98 look.I simply disable all the effects on Win XP ( From my computer-preferences-visual effects-adjust for best performance ) and i don`t use a background image.

I do not put themes to my PC but it is very important for my mobile. I was heart broken to find out that I couldn't change the theme for my new Android phone.