Employment contract - need help

I'm drafting a new employment contract and I could do with some help.

I need to put a clause in there that stops a graphic designer leaving my company and deciding they are going to approach all my customers and offer there services.

What sort of text/phrases do i need to use? anyone got any experience of this.
all very legal

Looking at your link nothing in law is straight forward.

I was hoping to pinch a bit of text that some other company uses in the employment contracts. I'm a lazy so & so.

I network with a employment lawyer and she is drafting a clause for me to insert, but I just though some one on here might have a well worded bit of text they might be willing to share.
Its already been risked - last designer still has half the design work created here on his site.

I have a friendly employment lawyer making a few adjustments to my standard employment contract, will share the pearls of wisdom when its Finnished.

Just like to get anyone else's take on the hole designer leaving and trying to get work from former clients.
I think there are two issues here:
1. Approaching clients having left the company.
2. Featuring design work as part of a designer's portfolio.

Point 1 - is obviously just out of order, unless the client contacts the designer directly (i.e if they really like the design work/style and see that that comes directly from a particular designer that they get on with etc.)

Point 2 - it's reasonable to use work as part of your own folio or for PR purposes as long as the work is somehow credited back to the original company. If a designer has designed something while working at a print company, then presumably the print company could/would still be getting the print side of things.

Of course, if the original contract stated that the designer wasn't allowed to use the work for PR purposes after leaving the company then the designer should stick to that.

This is just a personal view and a designer will always have design work in their printed/physical folio that they show prospective clients/employers so there's no way of policing that. It's the way of the world that a lot of folios are now online...
I think the basis of most restrictive covenants is that departing employees are forbidden from taking company data (in the form of client information and other commercially sensitive stuff) off-site and exploiting it for their own/a competitor's commercial advantage. In that sense, it's not on to approach clients known to you through the vehicle of your former employer and, while it gets muddy if they approach you direct, the question would be how did they find out you were offering the same service independently? (Answer: you told them, which amounts to the same thing). I think the cloudiest part of the whole thing emerges where a company is directly interfering with someone's right to make a living.

On the issue of portfolio material, it's a question of ownership: if you produced something as an employee it belongs either to the company or the client - I've found, however, that where the material produced is in the public domain, it's really just a matter of doing the courtesy of signalling your intention (depends largely on how amiable the relationships are).