Being there for your customers when they need you is what fuels your reputation. It's an up-front illustration of your values and intent, that lets your customers know that you're professional and business like.
If your IT is the stumbling block that means your responses are always shrouded in excuses for delays, you will be disappointing your most valuable asset, your clients. If you're providing a service to large companies or professionals with high aspirations and expectations, 'the computer's on a go slow today' is no excuse.
If your systems are inadequate, making you look, unprofessional and makeshift, that's exactly the slot you'll fill in your customers' minds, and unfair though it may seem, they're unlikely to buy from you.
Consistent, stable and high performance IT is one of your most valuable marketing investments, which helps your business perform the way you intended it to.
Get it right from the start and you'll really pull the rabbit out of the hat.