IBM doesn't use anything special for RAM. One nice thing is when you get a Thinkpad with 512MB it ALWAYS comes with a single 512M module, not (2) X 256MB. IBM always leaves one slot open for upgrades.
If the Thinkpad comes with 256MB, just take it with the 256MB and then get (1) X 1GB or (2) X 512MB. The (2) X 512MB will cost much less, and you can just pull the 256MB that it comes with. (this works for T42's. Keep in mind that some X series Thinkpads have the base memory soldered in.)
Go to www.crucial.com
and order an upgrade for your Thinkpad, they are guaranteed to work and have lifetime warranty. Your IBM warranty would not be affected if you don't damage anything putting the module in (you won't), but personally, if I had to send a Thinkpad in for service, I would put it back "stock" to send it in. If you get one with onsite service, I would have it stock before the technician arrived.
Go to www.thinkpads.com
and view their forum. Most Thinkpad owners use www.crucial.com
for their RAM upgrades, but any reliable RAM source should work fine, such as Mushkin, Kingston, etc.
Originally Posted by stpong
Oh, and I meant to ask, IBM charges a ridiculous price for RAM upgrades. I've seen notebook memory much cheaper, but I am wondering if the specific RAM that IBM uses in its machines is better or more reliable in any way. Also, does upgrading RAM on my own void my warranty?