|First I think you meant 500 GB rather than 500 MB.|
The Acer Aspire 3000 series does NOT support 48bit LBA due to both the motherboard and BIOS not being 48 Bit LBA capable.
This means you are limited to hard sizes no greater than 137GB. The common largest size below this limit is 120GB.
See more on 48 Bit LBA here
☺ When everything else fails, read the instructions.