I would get a hardware firewall. Doesn't slow down things (noticable) and is much safer than a software firewall. A suppost should stand in front of the door, not behind it. He must prevent not wanted people from comming in, not let them in first and than have to get them outside.
You bet a Hardware firewall is definitely a good choice!
However, I also have a software firewall installed for those times I take the laptop away from my network (D-Link Router) into the public areas...Internet cafes etc. etc. 
The problem being most hardware firewalls unless they specifically state it don't have outbound protection, see #### below. Whilst most routers now have a firewall, it shouldn't detract from your providing outbound protection.
Not all malware comes from the internet, with according to avast iNews recently 1 in 7 or 8 infections come from infected USB flash drives; so a hardware firewall is useless against this kind of malware attack.
Whilst if you can guarantee your system is and will remain clean then outbound protection is much depreciated, but the majority of people simply can't guarantee that.
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Any malware that manages to get past your defences will have free reign to connect to the internet to either download more of the same, pass your personal data (sensitive or otherwise, user names, passwords, keylogger retrieved data, etc.) or open a backdoor to your computer, so outbound protection is essential.
If there happens to be undetected/hidden malware on your system and it makes an outbound connection, any resulting inbound connection will be allowed as it originated from your system and it doesn't matter if you have a hardware or software firewall.
Edit: typo
