need some help for Sony VAIO notebook PCG-z505LSK

hi all,its my pleasure to become a part of this forum,I can use a little help or to be sent in the right direction would be hugely appreciated...a friend of mine handed it down to me and it was sitting in his garage for about 4 years, i got it going and it works, but it is loud-ish and very sluggish and i know its about 4 years behind in updates and i dont know where to begin with these updates or upgrades,i even went to check out you tube and it wont play vids due to the browsers being behind in the times..lol  OK So! this notebook was originally built for windows 2000 but is running win xp with service pack 1...if you need more specs im looking then up now, but in the meantime i figured ill throw this thread out here and hopefully get someone that knows where i should start to update/upgrade this notebook and just get it running in top shape,well as best as i can with this 12 year old machine, so if anyone has any directions for me to get started i would be hugely thankful being i need my own computer to start these online classes, so thanks in all in advance for any feedback whatsoever...Jaybean   

thanks for you response but i have ran into a bit of a dilemma now, there are two accounts to log into and one of them needs a password the other i can log right in..but wouldn't you know it the one that needs the passcode is the one that has the admin priorities and without it i cant do a thing...no updates.. no defrag... nothin, i looked up ways to legally hack and i tried some and they are not working but yet there are comments from numerous people who say they got theres to work...i dont know what to do...i sure wish my friend had a better memory..lol..any suggestions.. thanks<<<