What motherboard was it? What processor? I'd guess DDR400 SDRAM, being one of the most common memories of recent years. Maybe DDR333 if it wasn't a great PC.
It's not DDR, got 3 nothces. It's SDRAM, gota work out if its PC66, PC100 or PC133. That's the tricky part. I'd just read the writing off the chips and plug it into google.
Yeah, definitely not DDR due to the 2 notches. It's plain old unbuffered (non-ECC, non-registered) 168-pin SDRAM. As Davo said, google the chip markings and you should be able to find the speed.
As Forbin said. It`s probably a 128M stick, maybe 256 if you`re lucky. If you can still stick it in your machine (if it`s not sold or in pieces), download cpu-z - http://www.cpuid.com/cpuz.php and it`ll give you the info.