I've seen a few variations on this question come up recently, generally of the form:
"We have Windows XP clients and require IIS 7.0 to be installed on them when our application is installed on them. Is there a redist?"
In short, no.
(Note that this question is distinct from "how can I install and configure the OS version of IIS when I install my application", which is not covered here)
Since Windows 2000 and IIS 5.0, the only releases of IIS we've made have been a part of the operating system they're installed with.
The table of available versions looks something like this:
IIS 4.0 - NT 4.0 Option Pack
IIS 5.0 - Windows 2000
IIS 5.1 - Windows XP 32-bit, (?and Itanium, from memory?)
IIS 6.0 - Windows 2003, Windows XP x64 edition
IIS 7.0 - Windows Vista, Codename "Longhorn" Server
Since the NT 4.0 Option Pack, there's been no separate release of IIS.
So, if your app requires IIS and is targeting Windows XP clients, you need to target an IIS version as low as 5.1.