For
Illustration, there's Adobe Illustrator CS3. You can download a free sample of it to see if you like it
here.
But for Photo work & tons of flexibility, there's Adobe Photoshop & they, too offer a trial download
here.
For page layouts & catalogs, there's Adobe Indesign which I love! Again - they offer a free trial
here.
If you can get a Mac, get the IWeb package for any web, newsletter or quickie layouts.
30 day free trial
They are all pretty expensive, but worth it IMO.