what is difference between XP pro and XP corporate i can have both which should i install

XP Corp is also XP Pro without the need for activation.

Well if you bought Xp home and have the activation Key, by all means use that version...then you wont have to deal with changing the corp keys to install Sp1

-Drew

if i install the corp copy can i install the sp1 from the net or need to get the modified sp1, the thing is pro version come from the net and the corp come form a guy and he say it from the computer guy from his office. let say i install the corp copy and turn out it a to be a copy from the net and i try to install the sp1 unmodified will i have problem?

from what i read i cant install sp1 even if i have a legit copy of xp corp?

from what i read i cant install sp1 even if i have a legit copy of xp corp?

that's not true. i installed SP1 right over my corp copy

Me too, absolutely no problems at all. make sure you check your installation I.D is ok, look at the guide for changing XP keys under Guides section.