Almost every single app you need for windows can be found in linux.
For example http://www.gimp.org/ is prob the best photoshop alternative, it is rather powerful (although confusing to start working with it if you never worked with it before). Most people generally do not need any more features that photoshop offers

If you use Ubuntu, all you need to do is search in Synaptic to download what you want.

Alternatively you can also check the getdeb community repositories here: http://www.getdeb.net/updates/ubuntu/9.10/

If you have to absolutely have a certain windows application what doesn't get along with wine. Follow these steps:

1. Get VirtualBox by Sun here: http://www.virtualbox.org/
2. Download a slipstreamed Windows XP (or Win7) ISO from whever
3. Mount the ISO into virtualbox, and your running windows within linux, you use both at the same time as you see fit.