I have a HP Pavilion a1133w (PY030AA-ABA) with one gig of ram memory and I am interested in upgrading. The unit have the original manufacturers furnished memory installed which is: PC2-3200u-333-12. However, when I go to a memory supplier's webpage input the manufacturer's information the results I get are indicative of PC2-5300 as being the memory used in this desktop. Will the PC2-5300 work in this unit and offer a speed advantage or am I limited to using the PC2-3200u-333. One other question: what's the difference between the PC2-3200u-333-12 and PC2-3200.