Group Policy allows a manager to implement a consistent policy and enforce
it across multiple machines. This is mainly done in a domain structure
which requires Pro (windows 2000 or xp) workstations, and Windows 2000 or
newer server versions, although it can be done, as I vaguely understand it,
even in a workgroup environment with some extra effort.
I suspect the only folks using this at home are geeks learning about the
process or practicing it as a learning experience or to experiment and see
what is possible. You can lock down a machine to quite a significant
degree---including locking yourself as an administrator out of all access to
the machine--a mistake that isn't as uncommon as you might hope.
I don't expect to use the managed version of Microsoft antispyware even in
small office of a couple of dozen machines. I don't lock those machines
down now in any way, and I don't expect that to change.
Different strokes for different folks, though--I'm sure there are other
offices of similar size which lock things down--the organizations I work
with haven't felt that need.
Group policy, and/or the managed version of Microsoft Antispyware won't make
your machines any cleaner. I believe both versions will have the same
capabilities with regards to removal of spyware and real-time protection.
I use XP Pro at home for several reasons. 1) I work with it at work and use
it as an administrative workstation to administer domains. I want the
ability to join those domains sometimes, which XP Home can't do. In general
that doesn't matter to most users. 2) I really like the Remote Desktop
feature and use it all the time for remote admin work--I like having that
feature available, and 3) I can get some software at very inexpensive rates
through Microsoft's benefits for its MVP's, so that makes it easier for me
to use the fancier version.
I think XP Home is an amazing bargain--and entirely appropriate for the vast
majority of home users. As usual in newsgroups there's a good deal of
strong opinion about this and you'll probably hear from others. My view of
XP Home is that it is essentially the same code as XP Pro but with some of
the complexities masked and some features that aren't needed by home users
not available.
A better place to ask this question (home versus pro) would probably be the
public groups--microsoft.public.windowsxp.newusers might be appropriate, but
I'm not certain--I don't read that group so I don't know what it is like
except that it is intended to be a place where that question--home vs
pro--might get good answers.