Ques about windows xp HE Sp2 cd?

Hi, i am going to go to a custom cpu store to built my cpu, they told me if u already have a OS, bring it in and we'll deduct some money from it. And i was wondering i have a windows XP home edition sp2 cd, but it says "upgrade" in upper left corner of the box. If i give them this cd will it still work or will i have to purchase their win xp cd?