TMI is like the easiest mod to install. Here's what I do, it doesn't require winzip or any other program.
>Download TMI.
>Unzip TMI.zip. I have problems moving files from a .zip to another .zip, may be the same for you.
>Change Minecraft.jar to a .zip.
>Copy and paste all the TMI files into Minecraft.zip.
>Delete META-INF.
>Change Minecraft.zip back to a .jar.
Should work perfectly. Winzip and all other archivers are not needed imo, it just complicates things.