Originally posted by planetsim
1) Your connection will be much slower (depending on how many visitors you are getting)
I've had about 500 hits this month (ok, not many, but thats just under 100 per day) and neither I nor my housemates have noticed any change.
2) You will need to patch your system when a new patch comes avaliable
I have to do this with my PC anyway. It's no big deal to update my server too.
3) Software firewalls are great but you will also need a hardware firewall.
I have a router which provides NAT (I only have ports 25, 80 and 21 open) and I'm running a firewall on the server. Also, I don't run a hugely interesting site, so I don't think people are going to be that concerned. And I have up to date anti-virus software.
4) You should ask permission from your ISP before doing this, as they may disallow this and stop the service.
My ISP allows this. Yeah you should check, but I don't see how they can find out and stop you if you don't have much traffic coming and going.
5) Depending on who visitors your site, your chance of being hacked goes up. Quite a bit. Needless to say once your online your always a potential target.
Haven't you already asked this? See my answer to point 3.