NEVER, EVER download anything from anyone for windows unless it comes from windows download center its self. it can even seem official but people such as myself that know enough about programing and windows can, hide very mean viruses into your system and since windows conciders it a new part of your opperating system it can hide from virus scanners. so adhear to this advice, windows download center currently has the rc2 release the 3311 build, however, when windows does release the finial version of this service pack you will have to uninstall the rc version of this to reinstalll the finail, so just be patient.

Matthew go take a deep breath, pop another Valium and calm down. You're being a Paranoid Alarmist.

Shut up MATTHEW, do you receive checks or direct deposit from microsoft? Still working in the "find blogs or pirate sites and scare people" department? Have been downloading EVERYTHING from EVERYONE for windows since forever and never got any "hidden virus that can hide from anti-virus" What the hell does that mean? You are a crazy person who just try to scare people NOT to download genuine stuff of pirate sites.

Oh and by the way, I am typing this running build 5503... dont read to slow, you could get a hidden virus thru your eyes with my malicious writing skillz!!

do you actually know what a HIDDEN VIRUS IS? it cant be detected by virus scanners because windows counts it as an integral part of the OS, so virus scanners arnt allowed to touch it, which means it doesnt come up on virus scanners and so is a hidden virus, stupid!

I downloaded 5503 from binsearch.info and just installed it.
No problem at all, its almost impossible to break the Windows XP Security because it check all files on size, last modified date and all exe's have a security key certificate wich will become faulty after modifying it and as a result the setup wont even load.

The "hidden virus" mentioned above may refer to software rootkits http://en.wikipedia.org/wiki/Rootkit. Not all rootkits are malicious, for example Daemon Tools, but of course, some are. Rootkits can hide undetected from antiviruses or firewalls because they act as part of the operating system and they can examine every OS instruction, kernel-level or otherwise, to check if a directive merits cloaking or not.

It is true that a few bittorrent uploaders who are savvy enough in partial OS engineering CAN insert malicious code in the hacked up Windows XP SP3 they are sharing. So be very cautious, if that's the route you want to take. If you're still willing enough, it would be in your best interest to mount any downloaded ISO, and then fully scan/assess it first before finally using/installing it. Or be sure that you trust that pirate you are downloading from, unless it's absolutely OK for you to totally relax your security considerations.

Personally, I'd rather wait for the RTM SP3 version. In my personal analysis, there are no real considerable performance gains from builds 3311 to 5503 anyways.