Is it really better than windows, or is it just a great alternative? I've had Ubuntu sitting in my study for near half a year now and haven't installed it. If I were to install it, would I have to uninstall XP?
You CAN dual boot with Ubuntu and XP. (https://help.ubuntu.com/community/WindowsDualBoot) The choice, however, is yours. Is Linux better? Well, it obviously varies depending on who you ask. The official answer from the tech is the same answer to most questions I am asked: "It depends". I would have to say that if it has grabbed your interest, TRY IT OUT. Don't just go on what some people say about it. The fact is that millions have tried it and many love it and would NEVER go back to Windows if they have the free choice. Many also couldn't stand it, it was too hard to comprehend, and so forth. Windows got the same reaction, but they have MS behind them, so most EVERYONE has tried Windows. As for security and operability, I have to say that in general Ubuntu and XP are the same. What programs you find that actually work with Linux based OSs is an entirely different scenario, though. However, you may find that the programs you like to use are fully compatible with Linux (in other words, they have released a Linux version or have instructions on how to run the Windows version on Linux without problems). The other issue is hardware. You may find after you get Ubuntu on your computer that you have incompatible hardware. Some of these issues have known fixes that you can find with a quick Google search, some have no fixes at all. Best advice here is to have another computer around that can access the internet while you get Ubuntu installed and running.
I'm gonna say you don't do any hard-core gaming so yeah, Linux >> Windows. Ubuntu is the noobiest of all Linux's (still >> Windows though). It does all the configuration and stuff for you so its essentially the ease of Windows at a slight performance loss (by slight I mean ~20-30%). I'd still say Ubuntu is 50-70% faster than Windows though, more or less depending on how much crap you put on it Don't worry too much about software because there's a free (and better) version for any Windows program you would use frequently. If not, just start up Wine (Windows emulator). Your biggest gain with using Linux is the community. If you have ANY problems with your computer, getting in contact with thousands of Linux pros is a matter of signing up on one of the many Linux forums or going on an IRC channel. Personally I would not suggest dual-booting Windows and Linux. Out of habit, you will be spending 95% of your time with Windows (this happened to me when I first started using Linux). Only until my Windows partition was pwnt by a virus did I really start using Linux full-time. "Going back in case something goes wrong" is just a lame excuse people use to keep Windows. There's like a 0.001% chance of something going wrong that you can't fix. Oh, and my concluding statement: Linux has AMAZING eye candy. Compiz-Fusion is epic epic epic win - http://www.youtube.com/watch?v=Y4wB3GUemVw
I would suggest keeping windows... Unless you had a particular reason for switching to it... windows is fine for the average person.
My opinion on the top: If you want to use your pc for games or use purchased applications, you will need to know if they support linux (it is likely they do not), but I would suggest you to stick with Windows. If you want to use freeware alternatives to games (games like neopets not included because they are a web based game) and purchased software or just want to use your PC for daily tasks like email, web browsing, or even using it to edit or create pictures or videos AND not have to pay for any of it including support, go with linux. As someone said above, Ubuntu is very easy to install and will most likely be ready to used immediately after installing. There is a small learning curve, but nothing you can't pick up in forums. now for my 2 cents... I multi-booted XP, Ubuntu and Windows 7... I know, "why 2 windows OS?" I wanted to test out 7 beta and didn't trust it to be stable. The documentation is out there to do it if you don't already know. I love linux and would use ONLY Linux if I could get by without frustrations. There is a little more work to linux getting what you want/need for certain things (I'm sure there are some that could argue that repositories are easier than searching for what you want on google and just downloading it... but this is my opinion)... I really want Linux to me more widely supported as a consumer OS than it currently is, there are just some applications that do not run well or at all in Linux (again, you can google to find out what those are)... I know there is WINE and emulators and such, but it requires extra space and even then you aren't guaranteed your particular app will work without extra effort. Don't get me wrong, I like windows and wish it wasn't such a resource hog and didn't have the stability issues that it does have in some cases, but lets face it... if every game/application that was developed for windows would be developed for Linux, there would be a TON fewer windows users... If you use linux you know how many free apps, free support and how easy it is to customize it to look how you want... If you want your OS to LOOK like any version of windows but want the "dock bar" of a MAC, you can with linux without using a ton of resources...