purchased 2004 with 512MB of ram  processor 1.6

using 19.3 of 52GB capacity.

I remove cache every so often and defrag every so often.

I'm thinking after calling Dell Support to upgrade to 2GB ram.

I use firefox, thunderbird, windows movie maker, photoshop and expression web.

Will speed increase be more noticeable if instead upgrade to 1GB or for difference go for 2GB?

Oh and why is Dell not offering a 2GB upgrade for around $75.00 with shipping?

Thanks.