AGP Graphics Cards

[supermunki]

Hi there, sorry if this seems out of place, but I know little about the finer points of pc upgrading being a long time mac user, and this seemed the most appropriate of the forums I know to post this sort of question on. I have just bought a slim form factor compact evo (second hand) with a pentium 4 2.0ghz processor in order to have a cheap intel mac, and my issue is that it only supports AGP Low-Profile (half height) cards. I have found some some relatively unhelpful places on the internet that at least seem to suggest that an AGP Riser card will allow me to use a full size AGP card in my computer without issue. My question is if this is true, and what (if any) limitations are involved.

Another question I have is that I have also found much mention about low-profile AGP cards being sold as standard AGP cards and simply having a different bracket. Can anyone shed some light on this?

Thanks.