Upgrading E410 to E-3 / E-5?

Evening people,

New to the forum, and never bothered with them before but as I get more and more into my business I feel the need to get a bit more involved.

For the last three years I've been using my E-410 with the kit lens (14-42 and 40-150) and as I do property photography for an agent I also use the 9-18mm combined with the FL-36R and a cheaper slave unit with some cheap umbrellas / stands.

Now, I've always been fairly happy with the images, but my clients are now thinking about going slightly more upscale with their marketing, and I'm not sure my E-410 will really cut it.

Funds aren't exactly free flowing, so I'm looking to do this as economically as possible.  My thoughts really were to grab an E-3 body and utilise my existing lenses, and then upgrade the lenses at a later date as funds permit.  I know the SWD lenses boast ultra fast focusing, but as I do property, thats not exactly a bonus.

Really looking for anyones input, I know that putting the cheap kit lenses on an E-3 or E-5 is probably a little odd, but its only a stop gap until I can afford the higher end kit.

Is this a good idea?  Or should I can it and move over to Nikon / Canon?

To give you an idea of what work I do, here's the link to my flickr feed:

http://www.flickr.com/photos/51418979@N06/

Thanks in advance!