When you meet someone you always analyse how that person looks, speaks or behaves in that moment, and you keep that moment recorded in your mind as a first impression of that person.
And it goes both ways,
In a website it´s almost the same thing. When you enter a website for the first time it's that first impression that makes you stay for a while or leave immediately. And you don't even have to speak or make an excuse to leave in that moment.
"You don't get a second chance to make a first impression"
— James Uleman, PhD, a psychology professor at New York University and researcher on impression management.
You wear your coolest clothes to a first date or your first day at your new job. You make your best to look interesting and talk about all new thinks you heard or seen and try to look confident!
So if you want to make a good impression when you meet someone, why do you think that should be different with your company website. Update it! Know your audience and give them interesting and relevant content. Your website should look professional and make a good first impression!