WampServer

Hi!!
i'm new to use wamp. i've installed Php 5,mysql 5 & apache server in my system(i use win xp) already. when i installed joomla, i cudn't work.. Then i installed wamp & unzip it under my joomla folder, it creates apache,php,mysql folders bac again...tensed if it'l create any modifications to my earlier php & mysql, apache configurations so that i won't be able to run simple php-mysql programs even..
Also is wamp better to use in win xp os only ? ...i've win 2000 OS at home (in that i've installed apache & iis with different ports).

It'l b grateful if anyone can give some explanations to my doubts asap...

Thanks,
mss