Exhibit 23.1 CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS As independent public accountants, we hereby consent to the incorporation of our report included in this Form 10-K for the year ended December 31, 1999 into the Company's previously filed Registration Statements on Form S-8 (File No. 333-74173, File No. 333-74175 and File No. 333-86075) and Registration Statement on Form S-3 (File No. 333-90989). /s/ Arthur Andersen LLP Boston, Massachusetts March 22, 2000