Everything requires calibration before use. Adjusting your contrast, brightness or even switching to a different version of your graphics card drive will knock the calibration off a bit, so there's no way they can pre-calibrate them.
I've had no issues with side to side colour casts really. There is a very faint one when I first turn the monitor on, but after it's had 10-15 minutes to warm up, everything's peachy.
Your monitor should be usable out of the box, but you're basically judging it by eye (which is how monitor calibration devices do it anyway, just their eye is more accurate). You can at least get your contrast right using images like
this one. In the case of that image, the screen shouldn't be so dark or the contrast so strong that A & B and Y & Z merge into each other. You should be able to tell there's a difference between black & white and the boxes directly next to them (something which doesn't happen on my Emprex monitors, but is more than obvious on the HPs).
If you search
Google Images for other monitor calibration images, there are others out there that will help you with colour, but without a dedicated device it's pretty much impossible to get perfect calibration (but you can get "close enough").
I picked up the
Spyder 2 Express for calibrating monitors. It doesn't officially support multiple monitor setups, but there's workarounds. For a single monitor setup, it's a great device.
I mentioned the workaround for multiple monitor systems, but it really is a pain in the arse. Basically you have to reboot your PC several times switching monitors (how many times depends on how many screens are on the PC), and then once everything is re-enabled, the software just detects which monitor is on which display port and loads the appropriate profile for each screen. On the rare occasions it doesn't automatically pick up a monitor (eg, you have two identical make & model monitors on the same system), you can use
DisplayProfile to assign specific profiles to monitors in real-time (but you have to do this each time you reboot. Which is why I only reboot my PC about once every couple of weeks).
So, I'll be looking to pick up a
Spyder 3 Pro soon as it really is a pain having to go through all that lot every month or so (and the pro supports multiple monitor systems), especially when I have 2 PCs each with 3 screens (24" HP, 22" Emprex, and a 32" 1080 Sony Bravia on oneand a 42" 1080 LG on the other), another with a pair of 22" Emprex monitors (I don't use those screens for image accuracy, but I still want to get them as close as I can for watching the odd movie or youtube while I work), and a laptop to which I regularly attach an external monitor.