I hate it when they do that. We got in 100 PCs at work and every single one of them had their 128MB video memory pull from system memory. I tried to get my boss to send every dammed one of them back, but he refused. For some reason they never informed us of that "feature" when we were evaluating that purchase. I'm sure in the specs they had some murky jargon to identify it. What really made me mad was the eval PC they sent to us didn't do that. They claimed that their design changed during our evaluation, and we got the latest model release.
those PC's you have probably do indeed have a PCI'e slot so you could add in a good aftermarket video card. ;)