Exhibit 23.3 As independent public accountants, we hereby consent to the incorporation of our reports included (or incorporated by reference) in this Form 8-K, into the Company's previously filed Registration Statement as follows: Form S-3 Registration No. 333-27521 Form S-8 Registration No. 33-48874 Registration No. 33-83162 Registration No. 333-3570 Registration No. 333-3572 Registration No. 333-47767 Registration No. 333-51473 Phoenix, Arizona June 2, 1998 Arthur Andersen LLP 5