performance hit for replication

I'd like to create a fail-over server in case of a problem. Ideally, it
would be synchronized with our main database server, but I don't see any
major problem with having a delay of up to 4 hours between syncs.

My database is a little shy of 10 Gigs, with much of that data being in an
archived log table. Every day a batch job is run which adds 100,000 records
over the course of 3 hours (the batch job does a lot of pre/post
processing).

Doing a restore of the db backup in vmware takes about 3 hours. I suspect a
powerful server with a better disk setup could do it faster, but I don't
have servers like that at my disposal, so I need to assume worst-case of 3-4
hours is typical.

So, my question is this: My server currently works great, performance wise.
I need to add fail-over capability, but I'm afraid that introducing a
stressful task such as replication will hurt my server's performance. Is
there any foundation to my fears? I don't need to replicate the archived log
data because I can easily restore that in a separate step from the nightly
backup if disaster occurs. Also, my database load is largely selects. My
application works great with PostgreSQL 7.3 and 7.4, but I'm currently using
7.3.

I'm eager to hear your thoughts and experiences,
--
Matthew Nuzum <matt(at)followers(dot)net>
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