I’d suggest this should be a very important strand of your marketing message.
I recall being at a networking meeting once with a woman who was reputed to be very good at marketing, and, I’m sure she was – her track record supported her reputation.
In any event, she was explaining how, if she had to say one thing (and one thing only) to a customer then this is what it would be ….
She speculated that by far the single most important marketing message you could give to desired and prospective clients is your track record, i.e.: who else you provide your service for.
From this information, your prospective clients can quickly deduce if you’re appropriate for their business. It helps if you can also supply similar businesses in terms of size or vertical.
In my previous company I published details of all the projects/wins we were working on on our website home page. It went something like this …. “We’re delighted to announce we’ve been selected to supply & install a new Server & Network for a local mid-sized furniture distribution company. This company selected us over other possibilities because we had demonstrable experience is installing and running multi-site similar installations which was important to them”.
I used to make a point of watching our customers (and my friends) read our website and watched how they read our website. They quickly looked at the overall picture and looked at certifications, etc – then spent the majority of the time looking at our projects/wins, etc.
I’d suggest this should be the most important part of your website, and indeed your marketing material.