Sure when blocking something it might....but do you have a clue whats leaving your pc? Ever get a trojan....keylogger....you wont know that your sending information out from your pc for a long time. Not to mention, believe it or not XP firewall sometimes causes promblems when using messanger to send and recieve files. Oh you like ftp servering or downloading....uh uh...Give it up if you like XP firewall. Its a promblem child. Best bet if you want high security. Get a router with a built in firewall and runn a software app firewall! Which app is better.....who the heck knows, everyone has a different option -Chris