There are a number of ways to do this. Here's one method.

Right click My Computer and select Manage from the menu.
In Computer Management, click on Local Users and Groups in the left hand column.
In the right hand pane, double click on the Users folder.
You should now see a listing of all the User accounts on your computer.
To create a new user account, right click an open spot under the list and select
"New user" from the menu.
Enter a name for the new account. Note: You can create a password at this time
if you want and also elect to have the password not expire.
When your done, hit the Create button.
Hit the Close button.
You should now see the name of the new account added to the list. Right click on
it and select Properties from the menu.
In the properties sheet of the new account, click on the "Member of" tab.
On the Member of page, hit the Add button.
In Select Groups, hit the Advanced button.
In the Select Groups dialog, hit the Find Now button.
Click on Power Users in the group listing.
Click OK three times.
Close Computer Management.
Log off from your current account and log on to the new account.
Create a password if you didn't earlier.

An alternative approach would be to create a limited account through the User
Account applet in Control Panel and make the account a member of the Power Users
group in the Local Users and Groups console (Start -> Run -> lusrmgr.msc),

Good luck

Nepatsfan