Souk,
You live in a fairly big city, how about taking it to a Best Buy or such and paying the tech's there to put the memory in there?
Tell them that you want one 512 chip and have them install it. If it works then take the computer home and remove the chip and go on the internet to buy two more for a much better price.
If the computer works fine with the 100 chip and not the 133 then I would not try the 133 anymore. You could also take the chip AND THE COMPUTER back to the store where you bought the 133 chip and get them to plug it in and go from there. Maybe buy a larger 100 chip from them and personally I max out the RAM in any motherboard I have. If it will take 2 gig, then buy 2 gig. You will be amazed at the performance increase.
Now after you get it running like this, and are happy with it, next is a larger and faster hard drive. You probably have a 20/40 gig 4500 rpm hard drive in it now? Buy a 80 or 120 gig hard drive running at 7200 or 10,000 rpm and keep your old "C" drive in the computer, but make it the secondary "D" drive with the new drive as the boot up drive.
Would make the computer much faster and total cost would be $200-$250 and make it last another 2 years or so.
Joe
PS Hi back.. when's the ceremony and where?