I've downloaded and extracted ConfigMgr07SP2Upgrade_RTM_ENU.exe to upgrade my Sites to SP2. However, I've noticed that some files have a size of 0 bytes.

For example if I look under C:\ConfigMgr07SP2Upgrade_RTM_ENU\SMSSETUP\CLIENT\I386 I see the following files are zero bytes in size:

msrdcoob_x86.exe  0 KB
WindowsUpdateAgent30-x86.exe  0 KB
wmirdist.msi  0 KB

Also everything under the BITS 2.5 and BITS 2.0 subdirectories are also all 0 KB.

Contributed By: Cliff Hobbs [MVP ConfigMgr]
This is normal and nothing to be concerned about.

ConfigMgr has a number of dependencies on redistributables that aren't part of the core product itself. At the time you run Setup part of the process involves running the Pre-requisite checker to ensure everything that Setup needs is available including the pre-requisites and non-core redistributables. You can either let Setup download the files from the Microsoft web site at the time Setup is run or if you prefer you can pre-download them into a separate directory which you can point Setup to when it runs.

The ConfigMgr build process uses a file called install.map which details the initial configuration of installed features for the Site Server, Client and ConfigMgr Console. In order for an entry to remain in install.map the corresponding file has to physically exist. This gives Microsoft two choices when it comes to the Service Pack downloads:

• Include all of the files referenced by install.map.
• Create "pointer" files for the non-core ConfigMgr files to reduce the size/ disk space requirements of the Service Pack download. 

Microsoft decided on the latter by creating zero byte files of the same name for the non-core files to keep the Setup process/ install.map happy. This approach not only drastically reduces the size of the Service Pack download, it also saves you having to re-download the non-core redistributables again (once as part of the Service Pack download and again as part of the Setup process). When Setup runs, it will use the proper full versions from the pre-requisite download process instead of the zero byte files in the Service Pack download.