This is not the latest patch, but your installation must include this patch (or be Enhanced Edition of The Witcher) in order to apply the newest patch. Versions of the patch 1.4 downloaded before August 2011 will not work.
File integrity Edit
To check the integrity of downloaded files, one can use an MD5 hash to calculate the MD5sum of the downloaded file and compare it with a known good sum. Below is a table of known good MD5sums (the list will be fleshed out shortly):
|TWEE_Upgrade.exe (August 2011)||393B4783F2D6B906A6EAEA3D927B4A92|
|TWEE_Upgrade.exe (Bad, pre-August 2011)||9ddbb3baf43c8a7236ce1c2e3c038249|
There are many tools that can calculate an MD5sum, for reference one can use the freely available MD5-Checksum by Nero because it lets you specify a known good MD5sum and it automatically compares it with the MD5sum calculated from your chosen file.
Verification process Edit
Note: Please note that step-by-step description of the verification process has been moved to Patch 1.5.