ahhh a canuck. now the 3k - 4k makes more sense. that sounds about (aboot?) right then. what is it 1.60 to 1 now for exchange? anyways actually word is quite a pain to load.  maybe 2.4 512 is a lot for that.
Here is what you have to remember:
Your did is partially right about buying for the future. Since it is a laptop, upgrading is a bitch, so you do need to buy witht he future in mind.  What if your mom decided to expand her needs of the laptop and then needs to buy a 2.4 in a year? there goes that 2k you saved when you decided on the 1.8 instead. plus i think, buleyb can help on this, that celerons are not the best choice for laptops, due to various reasoning, 1 thing being battery life that will be affected.
bottom line is shop around, use online stores at least for comparisons.
when you do look you will see that the $$ diff between a 2.4 and 1.8 (of same proicessor) is very slight. almost the same as biggie sizing at your local wendy's/.