Windows ME Japanese running so slow

In my office We have 3 Japanese are used PCs which installed MS windows ME Japanese version ,and PCs spec are Pentium III 1 Ghz.,Ram 128 Mb,also MS Office XP (Japanese). Users found sometime difficult to move mouse (slow moving)and take respond timetoo much . Anyone face this problem before? Help me please (the last thing to do is Format and re-install)