More ram will only help you if you run multiple applications at the same time or apps that require a large amount of ram (ie: video games, video editing, large databases or spreadsheets etc).
Photo editors and graphic programs that have lots of images also require a large amount of ram but they also require a video card with lots or ram and a fast video processor as well.
If you're just surfing the web and not doing anything too ram heavy, you can do just fine with 448 (or 500 mb).
If you are buying ram there are lots of parameters to consider:
parity
speed
buffering
Make sure your mobo (motherboard) can support fast ram. Stay away from Factory Direct 2700 ram or the crap they sell at futureshop. That stuff is for consumers.
Check your bios or the manual for your mobo and see what your system bus speed is and what ram it supports. Then go to a place like Canada Computes and they will hook you up.
If your system bus speed is only 400 mhz (which it probably is considering you are only running a PIV 2.6 it is probably a northbridge) and it probably only has a L1 cache of 512 k and is probably a 478 pin. You can go to
www.intel.com and download the processor identity utility.
If you are looking for a speed increase and your mobo supports a faster processor with a L2 1 mb cache and a faster system bus (800 mhz) you would do well to spend the money on a processor instead of memory. Just remember: everything is dependant on each other. Any link in the chain that is slow, will slow everything down as everything can really only run as fast as the fastest component.
not to complicate the matter further but your system speed is also dependant on your hard drive speed. The faster the spin (MOR ones are 7200 rpm now) and the higher the hard drive cache, the faster the data will be written and read from the HD.
Here's a bit of lore for you:
My first computer in the early 90's was a 486 running windows 3.1 4 mb ram and a 20 mb hard drive. I upgraded the ram to a whopping 20 mb for $900.00.
I am running a ATI vid card with 256 mb video memory. I can effectively load my first OS, all my original apps, everything into my video memory and still have 200 mb left over. Crazy Huh?