Quick guide written by friend on MSN for me a while ago so please excuse the language:
first of you need to scale your texure to a fitting size, 512x512, 1024x1024 ect
then you "offset" the picture by half, so if 512x512 then you offset it with 256x256
then you have all the edges in the middle
then you just cover em with the clone tool
or you can blur em
but that makes it look blocky
Actually you can see if it will tile properly from within photoshop itself. Select your whole image(must be flattened) with ctrl+a, then go to edit: define pattern. Then make a new document that is many times larger than your original texture document, and go to edit: fill. Fill it with the pattern that you just made. Tah dah. Very Happy