offline files as performance booster?

Is there any way to use offline files to enhance performance when accessing a
network share?

I'm in the scenario of regularly accessing a file structure with a lot of
both small and large files, and this being done over the network is killing
performance. The structure is mostly read but there is some writing as well.
Things are a lot faster if I put the file structure on local disk, but this
is data that I would really like to have on the server...

So, my questions are:

1) Can I benefit from an "offline files" cache while still being online so I
get (transparently) mostly local disk accesses?

2) Are there big differences in performance for network share access and/or
offline files caching with different combinations of Windows OS's?
My environment looks like this:
XP (client) <--100mbit--> Vista 64 (server)
(Server doesn't have SP1 yet, and network will be upgraded to gigabit soon.)
I realize this is not the optimal setup, but are the potential improvements
(Vista offline files and SMB2) big enough to warrant the pain in
reconfiguring everything?
And would a real Windows server OS make any difference here?

Best regards
Mike Wilson