I have been having problems with pasting from Word into Wordpress for a while now and it was starting to drive me mad, as I do a lot of pasting from other chat room resources.
Thanks to James from webmaster talk who told me there is a special feature in Wordpress to deal with this.
Goto Write on your blog
Under the Title of your post you have got the icons, click the last icon (next to the question mark icon)
Should give you a new toolbar, on that toolbar there is a paste from Word option.