Appears like a corrupted jar-file to me.
Try redownloading.
As well, you're not meant to unzip the jar-archive, in case you did.
I'm on a mac so i can use winrar or 7zip so i just made the minecraft.jar into a folder would that be the problem. and if so do you know of any programs like winrar for macs
i just tested and its not because of smart moving
i get this crash when i install
QuoteDisplay More--- BEGIN ERROR REPORT 65844eb7 --------
Generated 1/7/12 11:45 PM
Minecraft: Minecraft 1.0.0
OS: Mac OS X (i386) version 10.7.2
Java: 1.6.0_29, Apple Inc.
VM: Java HotSpot(TM) Client VM (mixed mode), Apple Inc.
LWJGL: 2.4.2
OpenGL: ATI Radeon HD 6970M OpenGL Engine version 2.1 ATI-7.14.5, ATI Technologies Inc.
java.io.EOFException: Unexpected end of ZLIB input stream
at java.util.zip.InflaterInputStream.fill(InflaterInputStream.java:223)
at java.util.zip.InflaterInputStream.read(InflaterInputStream.java:141)
at java.util.zip.ZipInputStream.read(ZipInputStream.java:154)
at java.util.zip.ZipInputStream.closeEntry(ZipInputStream.java:100)
at java.util.zip.ZipInputStream.getNextEntry(ZipInputStream.java:78 )
at ModLoader.readFromModFolder(ModLoader.java:1287)
at ModLoader.init(ModLoader.java:826)
at ModLoader.AddAllRenderers(ModLoader.java:186)
at wb.(wb.java:76)
at wb.(wb.java:9)
at net.minecraft.client.Minecraft.a(SourceFile:265)
at net.minecraft.client.Minecraft.run(SourceFile:644)
at java.lang.Thread.run(Thread.java:680)
--- END ERROR REPORT 41a14888 ----------
If you know what this means and how to fix it please do share 
</init>
