Like shotgunefx, I don't see any reason why your first code snippet wouldn't work.

To answer the one question he didn't, inside double quotes variables are substituted and backslash-escapes are processed. Inside single quotes, they are not. So:

$a = "fred";
print "$a\n";
# prints fred
print '$a\n';
# prints $a\n
[download]

See Quote and Quote-like Operators.