If you're going to make some graphics (logos, etc) its best to use Photoshop, although if you like some of the features of Word, you can do it there. You could even copy some of your work from Word into Photoshop if you wish. I'm not sure how eBay works, but I'm assuming that they require a bit more than graphical elements. You could make a webpage in Word, however, if you have other programs such as MS FrontPage, its better to use them.
NVU is also a web site making program click here (it's free!)