Hi,
my specific brand 3450 was one of these: http://www.sapphiretech.com/presentation/product/?cid=1&gid=3&sgid=307&pid=164&psn=&lid=1&leg=1 .
This card also has onboard HDMI audio which is passed through the DVI port and this is indivudlaly listed as a passthrough device in ESXi. I have not tried it as I dont have an HDMI tv, and im passing through my Audigy 2ZS for audio already anyway, but it might be of interest to you if you do... I have also just passed the ATI card and not passed this HDMI audio device and thankfully the card still works perfectly on its own, which means you wont be forced into having to pass this extra device through in case you are tight on free passthrough device assignments (max of six).
Similarly, the Audigy2ZS has three passthrough devices separately listed, the audio card, the gameport and the firewire port - and thankfully once again you can pass just the audio card device through on its own without the others and it still works perfectly (altough as previously mentioned, analog output is horribly distorted, you must use digital out, which is perfect)..
I have been continually using my new vm with vga passthrough without issue over the past few days so it looks like its fully stable 
I just wish I had been able to get my nVidia 7200GS to work, as it is a bit better for custom resolution output than the ATI, especially with sub vga modes. Maybe with a bit of luck, someone will find a cheap nVidia card that does work 
Regards,
BAM.