as has been said before, html-signatures usually are a good way to go and there are two ways to include images with them:
• have them on a server
• send them with each and every email
I personally (and as far as I know many professionals who are dealing with email a lot) hate the second option, really. Images you send with every email (to make sure they will always be visible) just cram mailboxes and even worse: are shown as attachments.
If you have them on a server and include them via an image tag the user might get a hint that not all images are shown in the mail. But usually they know what that means and as long as you don't provide crucial data in that image it's way better to let the receiver choose if he wishes to see your ornamental fluff (sorry but seen pragmatically that's all it is) instead of forcing them to see it.
Also I think the image you're using at the moment is way to large... Just the logo should really be it. After all, you want your readers focus on what you write and not that monster at the bottom don't you? If you need such a large thing for advertising reasons or whatsoever you could still choose to have 2 sigs: new leads get the monster and longer conversations something more unobstrusive. Oh and it would make sense to change the name of the image to something like "AgentMail Logo" cause at the moment it shows up as "<image001.png>"