I wrote about this subject in a magazine article recently and this is a quick run-through.
There is really no good reason one would but WinZip. There is even less user to run WinZip un-registered. And if you have WinRAR installed you are doing it wrong twice. Two shareware programs instead of one free one.
There are plenty free and good alternatives. Just pick one...
7zip
www.7zip.org
This is a program that's been around for a while. Although it's UI might see a bit outdated it more that compensates with it's features and speed. It can open ZIP, RAR and all other popular formats, and it sports it own 7Z format that is quite good.
It is cross platform as it runs on Windows, Linux, OS X and *nix platforms.
There is also a portable version of 7zip at PortableApps.

My grade: 4/5 - I love it and use it daily. It works rocks solid and fast.
IZArc
www.izarc.org
Probably one of the most popular alternatives of WinZip out there. It looks and feels very much like WinZip. It supports all formats you will ever need and is translated in many languages.
But it tends to be slow. The development cycle is not very smooth and home page is sometimes very slow or even unavailable.
There is a portable version available, but it didn't work for me.
My grade: 2/5 - There are better apps available.
ZipGenius 6
www.zipgenius.it
This is an Italian piece of software which is refreshing. Most of other archiving apps come from eastern European countries. Again, it looks and feels almost like WinZip.
It is fast and works with all popular formats. Only thing that I didn't like is poor progress indication with some archiving operations.
My grade: 3/5 - Cool app. Check it out.
TUGZip
www.tugzip.com
Just another WinZip clone. I looks promising and its feature list tells that it does everything, but it didn't for for me in Vista. So no real test here.
Author suggest on his site that he will not continue development, so I would recommend you don't get attached.
My grade: 1/5 - Stay away.
ALZip
www.altools.net
I never heard about this archiver before. And it sure is a pleasant surprise. It definitely the best looking (or should I say cute?) app of all listed. And what came as another surprise: it's the fastest.
It is a clone of WinZip, it does everything you should need, works just fine on Vista and it's updated regularly.
So what is there not to like? Ads. There is a small ad visible all the time, but that shouldn't stop you from using it. It not very obtrusive.
My grade: 4/5 - Tools you should install on your grandma's computer. And yours if you don't like 7zip.
Honorary mention
If you are looking for a state of the art archiver and you are prepared to open your wallet, I would recommend you spend your money on PowerArchiver instead of WinZip or WinRAR. It's cheaper and better. I have a licensed version on all of my private computers.
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