HI!
Ram should not be a problem. they say it is recommended, but u can run with less, MORE is better!
When you start up, u get a blue screen? (BSOD)
Or when u go past the first part of your pc logo and then boot up to 'windows'?
If you just get a BSOD when you switch it on, then u have other problems. your disp card is not supported or something.
If u get a BSOD(blue screen of death) then, u might want to have a look at your windows, it might be hurt/damaged.
Try repeatedly pressing F8, 2-3 secs after you switch on your pc. u will get to a option screen that asks things like: safe mode, normal mode and Use most recent settings that worked. use the last option 'Use most recent settings that worked' and boot into windows with that, if that does not work, repeat the first step, and use safe mode!
If that still does not work, see your local pc docktor/repair shop.
Good luck!