I have been having memory upgrade issues with my machine which is a HP Pavilion XL754 that originally came with only 64MB and WinMe that I upgraded to WinXP Pro. For some odd reason I can't seem to get my PC to run with anything more than 320MB. which now is only at 256MB since the 1 64MB. stick somehow went bad while trying to upgrade using a PC100/133 stick that did not work. I ended up purchasing another stick of 256MB PC100 and added it and for some reason it still won't boot up. I keep getting a selective screen that asks which kind of boot up that I want but keeps ending back up on my screen without Windows even booting up. I checked the BIOS and it shows I am running 512MB so the 256MB stick that I purchased is being recognized but for some reason the OS won't boot up. I am getting really impatient now that this is the 3rd stick with the same outcome. I am hoping someone out there can guide me to get this thing working. Thanks

Some hP's are particular about what specific characteristics the RAM must have. Not all RAM's are the same - speed is just one factor. Go to www.crucial.com and see what you should have for that model and compare ALL of the specifics to what you got. Read the fine print about "only specific types of chips work" http://www.crucial.com/store/listparts.asp?Mfr%2BProductline=HP+-+Compaq%2BPavilion+XL+Series&mfr=HP+-+Compaq&tabid=AM&model=Pavilion+XL754&submit=Go Crucial guarantees compatibility, has a lifetime warranty, fast shipping and a reasonable price.