Don't do that, Windows boots from that partition, if you hide the System Reserved partition you will be unable to boot Windows 7 via the Chameleon GUI.
Instead, you should hide the Windows partition and rename the System Reserved partition.
Use
<key>Hide Partition</key>
<string>hd(x,y)</string> (x,y = drive,partition)
<key>Rename Partition</key>
<string>hd(x,y) Windows</string>
in your /Extra/com.apple.Boot.plist.
Please read the docs and the FAQ before asking basic usage questions.
Keep in mind that booting Windows 7 with Chameleon from another hard drive will break Hibernation and possibly S3 sleep as well.