I guess that you are in the tropics where you are and weather can be extreme. I know, I've been in the tropics many times having lived in both Africa and Singapore.
Most of us on the Seven Forums have settled for Windows Firewall, even though it only protects incoming by default. It is at least configurable in W7 for outgoing too, but it's rather complicated. Last time I tried my machine locked up.
I have mine setup as a quad boot - XP SP3 x 2, Vista SP1 and Windows 7 in that order, spread over 2 HDD's.
Been to Singapore a few times for shopping as it's just a 4 hour flight and weather makes it feel like home, easy to get out and walk and be comfortable. At moment it's like this here http://www.bom.gov.au/products/IDR633.loop.shtml I hate the cold, although our lowest is about 14 Deg C at night for a short time in middle of year so it's mostly just shorts and slip-on's all year round. 32-36C daytime.
I've never used the windows Firewall, but I'm behind a combined modem/router so reasonably hidden but as I said I just wanted to compare setups performance wise. Beta testing is so much fun.