Updated on 22 January 2010 for version 1.24d

As the name said, Warcraft version switcher will let you to switch between different version of Warcraft III. 

Download Warcraft III Version Switcher

Download version 1.21, 1.22, 1.22a, 1.23, 1.24 and 1.24b
NOTE: Version 1.24c and 1.24d IS NOT INCLUDED in this download.

Use 7-zip to extract the content.

Download part 1: Warcraft III Version Switcher.7z.001
Size: 90 MB
MD5: 0C3CC7FD53B4F06D65398C028A5534F6

Download part 2: Warcraft III Version Switcher.7z.002
Size: 86.8 MB
MD5: 97C4873D37BBEB6E1AEB238191749B08

You can download each version separately. Put the 'TFT Version 1.2x.zip' file in 'wvs' folder.

Separate Download

Main application (extract with 7-zip)
Download: Warcraft III Version Switcher.7z
Size: 550 KB
MD5: C1CFAC09DC21D0787DBE86BE07E4E38B

Version 1.21
Download: TFT Version 1.21.zip
Size: 29.6 MB
MD5: 75C19DB36653DEE7F37EAE27181CEFAC

Version 1.22
Download: TFT Version 1.22.zip
Size: 30.0 MB
MD5: A90D46567DE7614E340FC91512FE58DA

Version 1.22a
Download: TFT version 1.22a.zip
Size: 30.3 MB
MD5: 5B20F7B15A5E45657F3206CDB909164F

Version 1.23
Download: TFT Version 1.23.zip
Size: 53.4 MB
MD5: 3D80AF8D471DA28E00C283B81C6C15F0

Version 1.24
Download: TFT Version 1.24.zip
Size: 30.8 MB
MD5: 29D85101C4B7592499FB7EEBA5410371

Version 1.24b
Download: TFT Version 1.24b.zip
Size: 65.7 MB
MD5: 49CDD1798B3A9D2C63A716ECA8D4972D

Version 1.24c
Download: TFT Version 1.24c.zip
Size: 32.3 MB
MD5: 3BF252A1F4B1BE96FA1FA44FF0B67CBB

Version 1.24d
Download: TFT Version 1.24d.zip
Size: 32.5 MB
MD5: 95D096B723050194B152F719A94C42BE

Most of these files can be downloaded from Dota-Utilities.