Various torrents of the Windows 7 RC have been infected with a trojan that, if allowed to run successfully, could open a security hole in a user's system. The affected torrents have the setup.exe install file encapsulated in a self-extracting archive, along with an installer for the trojan itself; launching it triggers an install of both Windows 7 RC and the malware.
The advice is, as always, make sure to corroborate the MD5 checksum on your ISO download with the known, safe MD5, and if the two don't match then don't run any of the downloaded files. The good news is that anti-virus software appears to be catching the trojan before it installs, but better to be forewarned than rely on software.
While SlashGear doesn't advocate installing leaked, unofficial software such as this Windows 7 RC, we recognize some users will continue to do so. In the interest of security, the MD5 for the "safe" Windows 7 RC Build 7100 ISO x86 ISO is 8867C13330F56A93944BCD46DCD73590, while the MD5 for the x64 ISO is 98341af35655137966e382c4feaa282d. Far safer, however, is to wait for the official RC build, which is reportedly imminent.