Crucial.com or Kingston will tell you the exact memory module compatible for your notebook.
The PC2700 512mb Kingston RAM I got from Fry's Electronics on sale for 69.99 after rebate for my HPZT3000 would be the same used for the DV1000 (notebook memory).
Best buy had the very same Kingston PC2700 notebook RAM module 512mb RAM for 89.99 a few weeks back.
I have not seen this notebook memory on sale the past couple of weeks but if check the sunday newspaper adds for the electronics stores it will pop up (you want notebook PC2700 RAM not desktop RAM).
Also, outpost.com (Fry's Electronics website) has Corsair PC2700 512mb notebook RAM for 99.99 everyday.
You can order Crucial memory at anytime online but it is about $110.00 + shipping I think (check exact pricing yourself).
There is a pinned topic at the top of the upgrades area on X1000forums.com (same memory you would need) and you can also find the dedicated forum for the HP DV1000 (or search for this at google to find it) in the general section at X1000forums.com