Absolutely, get the 2nd RAM module separately but you would perhaps get the best bang for the buck ordering 512MB RAM.
If your Notebook uses PC2700 (333mhz) get that or if PC2100 then you could get PC2700 (backwards compatible if a better price).
Go to crucial.com or kingston.com and put in your manufacturer and system # to guarantee compatibility with that companies memory (also try Pnymemory which is sold at Circuit City/Compusa but has a website).
Many students and others at x1000forums.com order 256mb to save money and then add 512mb RAM for under $100 on sale for 768mb RAM total.
For example, I just bought a 512mb RAM module (Kingston PC 2700 512mb (333mhz) for 69.99 after a $20 rebate at Fry's Electronics (sale price good thorugh today -- Tuesday 8/17 - sale price in Friday newspaper).
If you are not on the west coast Compusa has PNY memory PC2700 512mb RAM on sale for 65.00 after rebates (through this week I think but not sure).
And, of course, Crucial.com is a great quality RAM that has everyday prices (and ships to you) but you will likely pay over $100 for 512mb RAM (but much less than that if you really only want to add 256mb) ..
Any recommendations on where I should buy RAM? Looking to move up to 512mb RAM and was wondering if I could get it cheaper than the $125 upgrade option when purchaing the notebook.