1. After installing can I still run Windows? (I seen grub and lido but don't understand what are they)
First of all before 'messing about' with your system two things:
1) DO NOT attempt a dual boot with Vista as it has a different booting process to previous versions of Windows (i.e. the boot.ini file is no more - and I found that out the hard way on a brand new computer which I could only fix with the recovery disc).
2) Ensure you have backups of all important files - don't take the common 'it'll be fine just this once' attitude because you never know and you may find out the hard way...
IIRC when I installed Ubuntu Breezy Badger to have a play about there are two useful features in the install:
- Firstly you should be asked to make a new hard disk partition and specify its size in Mb - it will make several partitions from some of the empty space (you specify the amount) on your hard disk and then format the empty space. By several partitions I mean Ubuntu needs several small partitions to run off of like one to store the boot records etc.
- There is an option at the end to install the GRUB Bootloader and if installed it will check for other OS's on the system and it will pick up Windows' installation (provided it isn't Vista - it may work with Vista I'm not sure as it's not something I've tried). On startup after the POST screen you'll get the choice which to boot (from a file on the Linux system rather than boot.ini) default is Ubuntu, but there are other Ubuntu options and also Windows should appear on the list.
There is a way of editing the necessary file to change the boot choice menu such as default choice, time to display, order of options, and even what options to display (much like you can in a boot.ini). Although I can't remember the exact method or the file involved as it is a while since I installed it.
There is also a way to get files from the Windows Partition visable on the Ubuntu system as well for easy transfers (i.e. it doesn't do this automatically). The WINE 'emulator' will also enable you to run .exe files in Linux (again which it can't do automatically).
As another point, dial-up modems will NOT work in Ubuntu without the required configuration file - available on the Ubuntu website I believe.
2. Can I remove Linux if I wanted to do it one fine day?
I believe so and I believe it is a painless process where you boot into the Windows installation and use a hard disk management tool. You would delete all the Linux partitions (easily findable by the file systems used IIRC) and resize the Windows partition back to the hard disk capacity (you'll be shown the amount of space available to resize and you'd select the maximum amount). It'll need a reboot and may display an error (I remember Paragon Hard Disk Manager displayed an error on the first boot up after a primary partition resize but was fine after that and the hard disk showed up in My Computer as its full size).
Regarding which Linux distribution is best, they all have their pros and cons and if you're serious about Linux being a viable alternative to Windows then some research would be needed into what you want from the system.
Linux is a good little system but be warned it takes time to get used to and certain admin settings need changed to make it work properly to your liking (I destinctly remember I had problems with something on Breezy Badger but I can't remember exactly what or how I sorted it out). Several commands on there need to be done on its version of the Command Prompt but once you get used to it, I'm sure you'll be ok.
It's been a while since I installed or even used Linux for that matter, so I can't guarantee 100% accuracy in this post, although I'm pretty sure most of what I wrote is correct regarding the installation of Ubuntu.
You do get a DOS installer with a help feature and it does ask for confirmation when it's needed and it installs a lot quicker than Windows but with quite a few prompts (which set the sytem up correctly from the off).
Regarding the running and operation of Ubuntu - I'd say your better off reading the manual on their site and also through forums about the system.
