Well, Bill Gates and Steve Jobs kind of made sure there was no such thing as ‘Universal’.
But if you know what program they are going to create the logo in, and what programs you’re going to use to make your letter head, etc… you’ll know what kind of image you need. It won’t be universal. You could use a small sized .bmp or .tiff file if you’re going to import the image into Word. I made a cheap version of letterhead once by just creating a header on a template with the image and info on it, just in MSWord.
But that same image won’t be suitable to say.. print tshirts with. They’ll want a large vector image. If your graphic designer is using Photoshop, you can get the image in several different sizes and types of files, according to what you’re going to use it for. Usually, people working in Apple products can convert some types of images for their use. I can’t open some types of Apple image files on my PC. They ended up sending me a .png file, that my windows image program could change into a .jpeg file.
I have a few different forms of my current logo now… a small version that I can upload onto the net.. a larger version so that I could have it printed onto a custom apron, and even one in ‘negative, just for fun.
Good luck!