Select performance vs. mssql

Hi,

I have some experience with MSSQL and am examining
PostgreSQL. I'm running under Windows. I like what I
see so far, but I'm hoping for some performance
advice:

1. My test database has 7 million records.
2. There are two columns - an integer and a char
column called Day which has a random value of Mon or
Tues, etc. in it.
3. I made an index on Day.

My query is:

select count(*) from mtable where day='Mon'

Results:

1. P3 600 512MB RAM MSSQL. It takes about 4-5 secs to
run. If I run a few queries and everything is cached,
it is sometimes  just 1 second.

2. Athlon 1.3 Ghz 1GB RAM. PostgreSQL takes 7 seconds.
I have played with the buffers setting and currently
have it at 7500. At 20000 it took over 20 seconds to
run.

5 seconds vs 7 isn't that big of a deal, but 1 second
vs 7 seconds is. Also, the slower performance is with
much lesser hardware.

Any ideas to try?

Thanks much,
Mark

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