looking for memory for slow computer

I notice computers running slower and slower these days. Including my own.

They still run into performance problems even after I reinstall Windows (usually XP), though it seems better for a while.

I think the problem was that these computers used to be acceptably fast when they first came out, but that Microsoft kept putting more and more junk into XP so that it taxes the system and it starts to run out of memory (and so goes to the hard drive to use virtual memory). That's my guess anyway.

So now I'm looking to upgrade memory.

A "standard" site to buy memory from seems to be crucial.com. They have a neat system scanner that scans your system, tells you what you have in your system, and makes recommendations on what to buy.

For example, my current system is a Dell Dimension 2400 with two memory modules (one 256MB and one 128MB, both DDR 2700). According to the scanner, "Each memory slot can hold DDR PC2700, DDR PC3200 with a maximum of 1GB per slot." That's good to know.

What's the difference between PC2700 and PC3200? (Shows you how out of touch I am these days.) The speed. PC3200 is the faster speed with peak transfer rate of 3200MB per second.

Let's see. Crucial is selling the 1GB module for $46.99.

[a couple days later -- actually the key to notice is DDR which stands for Double-Data Rate. I now see it's different than the old SIMMs. I assume the old SIMMs must be SDRAM (single data rate) See below.]

On ebay, I see two 512MB modules for $23.88. Only PC2100 DDR. Hey half price. 2GB for $54.48. Darn, free shipping only to 48 states.

OK, ramhut sells 1GB PC2700 for $38.95. $34.90 starting bid. I dunno. I might spring for the extra $8 and buy from Crucial.

deedan92: two 512MB modules for $24.88 (used).

fsgw: PC3200 1GB DDR SDRAM 1 GB PC 3200 DDR400 1G RAM 184 pin for $14.99 plus $6.99 shipping. So $21.98. Doesn't state compatibility though.

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[1/20] Looking to pop in more memory into Florida's computer which has only 256MB. I notice it takes DDR memory too. I found a 128MB DDR module (I think from Tanaka) and I notice it's physically different from the myriad other SIMMs that I have lying around. OK, so much for upgrading all these computers. [Ugh, popped it in anyway and now Florida's computer doesn't power up. I guess that was the original problem.]