LaptoP OverHeat?

WEll, a lot of temperature programs wouldnt work so i have to rely on HDD which only does my hard drive to make it work. o hwell. anyway,the temperature normally gets up to 130 degrees FARENHEIT by a few hours. my uncle told me that i shuldnt leave my laptop on all the time (i used to 24/7 have it on).

ummm....so basically its a dell inspiron 8200 with a p4 1.6 ghz 384 ram 40 gig hard drive running windoze XPee

i want to know whether its gonna hurt my laptop if i DO leave it on all the time, becuase it would be very helpful to me if i could but i dont want to endanger it

thanks