If I increase my DDR will that decrease the lag my computer is experiencing? My machine is about four years old and probably has half a gig on it. I can't really afford to buy DDR so if there are other free possibilities I'd like to try those first.

Well you could try defraging you PC and doin disk cleanups, that is what i would do anyway. It also could be your video card if it is lagging abit try updating your Direct X drivers. But really yeah if your computer is running slow it usually is the the RAM if you are running xp you should have 1GB vista 2GB for it to be smooth then again it could be your CPU. If all else fails do a fresh install of Windows.

I suppose a fair question would be, "did it lag before"?

If yes, then more memory and some management of running processes and startup programs would likely help. As you install more programs, many run at startup and also have auto-update processes running. Some AV programs use more resources than others

If "no", and this just started, you could have some malware slowing the machine down.

Also, as suggested above, defragging the HDD sometimes helps. Also, if your HDD is almost full, data access time will increase since the drive must initialize more data, and access time is slower. (HDDs are fastest in about the first third of their capacity).

So we're clear, XP doesn't really run well on only 512MB of RAM. When you take into account allocated video memory, and what XP needs to keep itself running, you're only left with about 100MB of free RAM on average. Firefox will use more than that with a dozen or so tabs open. At any rate, after available RAM is gone, the machine uses the page file to do it's thing, this is when every operation is routed through the HDD, and festivities grind to a slow crawl. So, the ugly truth is that you really do need more "DDR", whether you can afford it or not. (Sorry to report).

You might consider including your machine's specs. "My computer" is a bit too generic to be very usefull.

you didn't say how much ram you have. If you have less than 1gb on an XP system, it will run slow. but also read here: Tutorial: How to speed up your Windows for free

1) Absolutely many things to do try and speed up your computer for free (start with the link provided in Tedster's prior post is a good start) . Also see here

2) As you only have half a gig now on your computer then adding memory when you can afford it should also easily show you a quick performance boost return for the $$

wow..thanks for the guide,specially the one on stopping umnecessary services.

And re: un-needed services and startup programs.. here's another couple links you might find helpful

Black Viper's website

And to learn more about controlling startup programs as well as a startup program database to look things up see Pacman's Portal