The GT230 is an OEM only card. It is possible it does not yet have win7 support. I am coming up empty on my searches. You could always contact Acer support and tell them your issue. They may be able to help. However, they may not since Vista originally came with your system. Nvidia may have placed support for this product on the OEM companies and not on their own website. OEM only products are always funny like that.
hmm yeah ima contact ACER support and hope for any help