1. Create a dual-boot environment or (depending on how much RAM you have or how fast your processor is) install Debian 5/6, Ubuntu 10.04 or above, or Linux Mint 10.04 or above into a virtualbox
(for the sake of space and time I will not go into the details of partitioning or setting up your dual boot environment, there are many guides already available online that weigh the pros and cons of both, your computers hardware and specifics require different drivers and therefor your mileage may vary as far as setting things up goes)
One thing I noticed from your post is that you have 32-bit vista. depending on how your computer was optioned out from the factory when you purchased it, it may or may not have a 64bit processor in it, you'd have to look at it's specs in the Control Panel to be able to determine that. The reason this is important is because most ROM building is done on a 64 bit linux, if you were to install 32-bit linux on your computer you may not have al l the necessary libraries available for building and the build will probably fail. Therefore, if you have any computer in your home with a 64bit processor, use that one instead.
2. Once you can boot into linux the easy part starts and is separated into three main steps
1. Setup build environment
2. sync repositorys and download source
3. configure and "make" or "compile" the rom (this part is completely automated so as long as the first two steps are completed successfully you will get a flashable zip afterward)
Becuase you may not have any linux expirence and learning the terminal can be a bit tough for new users, I will leave you with two guides that will hopefully point you started in the right direction
This is the way to do everything "from scratch" it takes the longest but it insures you have a 100% completely customized expirence
Official Google Dev Guide
XDA guide
The second (easier) way, I might recommend for you is taking an existing 2.3 Gingerbread rom, and modifying it with the MIUI files
Mod Guide
THe only problem with doing it the easier way is it insures that we keep the screen bug as the drag and drop issue doesnt seem to be kernel related (just probably a bad build of gingerbread)
anyway, there are 100 different ways to build a rom, but this post should give you quite a head start