Backup your downloads first
IF you detest finding them all over again, meaning save them to a disk, etc.
After purchasing your computer, see
this
thread posted by Sleepycat first, very helpful.
First, you must install from the base game (The Sims 2), but before you install any other EP's (expansion packs), make sure you have the game patches from the official
EA website as well.
After you install Season, it would be wise hold off on using certain hacks of your choice, some arent full compatible with it yet. Remove the Insiminator and Inteenmainator from your downloads to prevent any conflicts untill they are fully updated as well. Hope this helps!