Z-M has asked an important question.
If you save pictures from websites to your hard drive, they're commonly between about 0.05Mb and 0.2Mb in size. (However they could be far larger if the site designer forgot to optimise them before putting them online). My 14Mp camera takes pictures, using my normal settings, that are around 0.7Mb in size but changing the settings to the biggest image size (and using the lowest compression) would take them to around 7Mb each.
So, if you wanted to store 1000 7Mb pictures you'd need 7Gb of storage capacity which, in practice, means using an 8Gb memory stick. However, since most amateur photographers don't use the maximum image sizes available from their cameras (which is pointless anyway, unless you want to make really big prints from them) most people could get away with using, say, a 2Gb stick.