general peformance question

Hi,
This a kind of newbie-question. I've been using Postgres for a long time in a low transction environment - and it is
great.

Now I've got an inquiry for using Postgresql in a heavy-load on-line system. This system must handle something like 20
questionsper sec with a response time at 1/10 sec. Each question will result in approx 5-6 reads and a couple of
updates.
Anybody have a feeling if this is realistic on a Intelbased Linux server with Postgresql. Ofcourse I know that this is
toolittle info for an exact answer but - as I said - maybe someone can give a hint if it's possible. Maybe someone with
heavy-loadcan give an example of what is possible... 

Regards
Conny Thimrén