when i run the download shortcut it says invalid file

i have a p4 3.2 ht with 1024 ddr memory 70g rapter hard drive with a 6600 nvida gforce4 and i do see the dos windo thats where is says program to big to fix in memory when i was downloading it seid that the file was invalid right at the end of the download i think the download some how got messed up

i just purchsed spartan on your sol and at the end of the download it seid invalid file and the app wont run?? it says in the dos windo that it wont fit in the memory program is to big i have 512m ddr2