OK, follows these steps:
1) Download whichever version .zip you wish
2) Extract the achive to a folder that's convenient for you. On my Win 7 install I have all my downloads go to a downloads folder under my user folder. So in there make yourself a syslinux.3.82 (or whatever version you get) and extract everything to there. I believe a right click in Win 7 will give you the option to expand an archive.
3) You go into the command prompt, run as administrator, just like you did.
4) you'll want to cd to something like C:\Users\Your User Name\Documents\Downloads\syslinux3.82\win32
The path may not quite be that, but what I have should be close enough for you to figure out the correct path
5) Now you can run the syslinux.exe command
The key here for you is that the syslinux.exe command isn't at the root level of the archive but in the win32 folder within that.
Mini1: Vostro A90, Black, 2G, 1.3 Webcam, Bluetooth, 64G SuperTalent, OS X 10.6.4
Mini2: Mini9, Black, 2G, 0.3 Webcam, Bluetooth, 32G RunCore, OS X/Win 7, internal PCI-e SHDC Reader
Mini3: Mini10v. Black, 2G, Webcam, 640G HD, OS X 10.5.8/Win 7/Ubuntu [Hibernate w/NBI 0.8.3 RC4] Dropbox Referral