Can you help me construct secure DIY network compatible alarm?

[tslugmo@xxxxxxxxx]

Here's the situation, it should be relatively easy. We've got one room
with two doors and a few windows along one wall that we'd like to
protect.  We're thinking two door sensors and one motion detector,
along with one siren.  Keypad only needs to be by one door.

There's no closets or anything fancy, just a plain room.  We don't have
a telephone line, though, just VoIP.  NextAlarm looks to be a good
choice from what I've seen.  However, we've got concerns about getting
the right equipment.

We'd prefer wireless sensors since we're leasing and there's no
drywall, only stucco walls.  However, it seems that the keypad for many
completely wireless alarm systems is also the brain, meaning that if
the keypad is smashed with a hammer, the alarm is disabled.  The more
expensive systems seem to have a seperate "brain" with a metal lock box
to prevent this.

I left a message and an email for Robert Bass but never heard back.
Anybody else care to sell us an alarm system?  We've found most sites
pretty confusing, and figuring out all the parts we need is tough.

One option that we were considering is putting that keypad/brain
somewhere hidden, disabling the sound on it so it doesn't alert the
robber to its location, and putting a second keypad on the wall by the
door.  It starts to get costly at some point, and might even make more
sense to get a phone line for a year and buy a cheaper system than one
that's network compatible.  Any advice?

Thanks,
tslugmo