If Operating Systems Were Beers ...
DOS Beer	Requires you to use your own can opener, and requires you to read the directions carefully before opening the can. Originally only came in an 8-oz. can, but now comes in a 16-oz. can. However, the can is divided into 8 compartments of 2 oz. each, which have to be accessed separately. Soon to be discontinued, although a lot of people are going to keep drinking it after it's no longer available.
Mac Beer	At first, came only a 16-oz. can, but now comes in a 32-oz. can. Considered by many to be a "light" beer. All the cans look identical. When you take one from the fridge, it opens itself. The ingredients list is not on the can. If you call to ask about the ingredients, you are told that "you don't need to know." A notice on the side reminds you to drag your empties to the trashcan.
Windows 3.1 Beer	The world's most popular. Comes in a 16-oz. can that looks a lot like Mac Beer's. Requires that you already own a DOS Beer. Claims that it allows you to drink several DOS Beers simultaneously, but in reality you can only drink a few of them, very slowly, especially slowly if you are drinking the Windows Beer at the same time. Sometimes, for apparently no reason, a can of Windows Beer will explode when you open it.
OS/2 Beer	Comes in a 32-oz can. Does allow you to drink several DOS Beers simultaneously. Allows you to drink Windows 3.1 Beer simultaneously, too, but somewhat slower. Advertises that its cans won't explode when you open them, even if you shake them up. You never never really see anyone drinking OS/2 Beer, but the manufacturer (International Beer Manufacturing) claims that 9 million six-packs have been sold.
Windows 95 Beer	The can looks a lot like Mac Beer's can, but tastes more like Windows 3.1 Beer. It comes in 32-oz. cans, but when you look inside, the cans only have 16 oz. of beer in them. The ingredients list, when you look at the small print, has some of the same ingredients that come in DOS beer, even though the manufacturer claims that this is an entirely new brew.
Windows NT Beer	Comes in 32-oz. cans, but you can only buy it by the truckload. This causes most people to have to go out and buy bigger refrigerators. Touted as an "industrial strength" beer, and suggested only for use in bars.
Windows 98 Beer	Comes in 16-oz or 32-oz cans that seem to create pockets where the beer just won't fill. With the extra money that Win98 beer costs, you get all the same features of Win95 beer but in a can that can be opened with one quick flick; however, the beer is no faster coming out. The can doesn't have any special design apart from the fact that the beer can only be extracted using a Microsoft drinking attachment. The can has been known to explode if the beer is drank too fast, too slowly or if the can is left sitting on the side.
Unix Beer	Comes in several different brands, in cans ranging from 8 oz. to 64 oz. Drinkers of Unix Beer display fierce brand loyalty, even although they claim that all the different brands taste almost identical. Sometimes the pop-tops break off when you try to open them, so you have to have your own can opener around for those occasions, in which case you either need a complete set of instructions or a friend who has been drinking Unix Beer for several years.
OS/400 Beer	Always packaged in a green bottle, some colorful labeling has been used lately; however, this does not disguise the fact that the brew has not changed in the last 20 years. Drinks very slowly, sometimes even pausing for no apparent reason.  The bottle caps are proprietary and require a special custom opener. If you buy a beer and don't drink it within a few months of purchase, you will be required to upgrade the beer before actually drinking. Comes in many styles (but still tastes the same), and some of the cheaper brands have been known to have a built in mechanism to make the beer flow even slower.
AmigaDOS Beer	The company has gone out of business, but their recipe has been picked up by some weird German company, so now this beer will be an import. This beer never really sold very well because the original manufacturer didn't understand marketing. Like Unix Beer, AmigaDOS Beer fans are an extremely loyal and loud group. It originally came in a 16-oz. can, but now comes in 32-oz. cans, too. When this can was originally introduced, it appeared flashy and colorful, but the design hasn't changed much over the years, so it appears dated now. Critics of this beer claim that it is only meant for watching TV anyway.
VMS Beer	Requires minimal user interaction, except for popping the top and sipping. However, cans have been known on occasion to explode, or contain extremely un-beer-like contents. Best drunk in high pressure development environments. When you call the manufacturer for the list of ingredients, you're told that is proprietary and referred to an unknown listing in the manuals published by the FDA. Rumors are that this was once listed in the Physicians' Desk Reference.