I don't know of any legitimate website that offers either of the Cameron Files games (Loch Ness or Pharaoh's Curse) for download.
(EDIT -- Marian found Loch Ness at Big Fish and apparently Steam now has Loch Ness too. Haven't found the 2nd Cameron Files game for sale as a download though)
If you're confusing "download" with "install from CD" and are asking if either game will install and work properly in Windows 7, neither game is listed as working on Windows 7 in the Windows 7 and Games thread, and there have been threads where people got errors about "not 64 bit compatible" when trying to install "Loch Ness" on Windows 7.
http://www.gameboomers.com/forum/ubbthreads.php/topics/879035/1The second one (Pharaoh's Curse) actually has trouble on some XP computers where the first one (Loch Ness) would work. These games are best played on a "retro" computer with Windows 95/98/ME -- or possibly played inside a Virtual Machine with Windows 95 or 98 or ME as the guest OS.
Anyway, if you already have the game CD's, you can go ahead and try to install the games and see what happens. But I wouldn't recommend purchasing these games for Windows 7 if you don't already own them.