I am looking to upgrade my compaq presario 5108us memory from 128mb 100 to two 256 mb 133 to give it 512 mb total. The trouble is I am unsure what I can actually use because the manufacture says I can use 100 or 133 and when I go to place an order the places I look to place an order says I can only use 100, I really am torn on this issue because I would like 133 for more speed but dont wanna buy something I cant use and waste my money. The part numbers that compaq gives me for these memory sticks are for 256mb 100/ #com04225 the other is for 133/ #com15581 but of course these are non existant when you do a search to do a comparison. Can someone help me to compare memory so that I get the correct one please? The memory I found is at http://www.compuvest.com/Description.jsp?iid=220025 and I am not sure if it will work. Thank you in advance for all your help!!!