Ignoring all the hyperboly and ranting going on I will answer that "Yes, SP2 is secure enough". Having said that I will also say that SP1a was secure enough, and SP1, and "original" XP. What isn't secure is the user. Through ignorance (not a put-down, just a fact) most users leave themselves open to attack while the tools to protect themselves go unused.
To put any consumer OS on the Internet without a firewall or NAT would be a huge mistake. Doing the same with anti-virus software is also asking for trouble.
What MS needs to continue to work on is not adding new features, but shoring up the basic security of the "plain jane" installation as a consumer would do it and offering wizards that will incrementally open features. Ideally my Mother-In-Law should be able to install Windows XP SPX and have it automatically locked down. Simple email and web browsing would still work and the flashy "cool" features she never needs won't present vulnerabilities.
Firewall and plain text email should have been made standard a long time ago.