There are some major downsides to driving a 507 this way. The VGA port is inteded for the occasional connection of your laptop, not a media PC. Stuttering due to frame rate conversion is the 1st thing you see on video, followed by tearing. Mnay people use a dual display card with the screen owing to the fact that HDMI, whilst smooth with PAL video, and obviously no tearing, is not very sharp, as you can't send native res via HDMI, only video resolutions. Also, the built in and non adjustable overscan leaves the taskbar off the bottom of the screen, so MCE front end is really needed all the time. Using VGA for normal windows stuff, and swapping to HDMI for games and video display is the way to go.
Some other plasmas have none of these drawbacks, like the PHD panasonics, or MXE Pioneers. In fact the MXE pio is probably the best HCPC display out there. The more commercially engineered panels are clearly intended for use with a PC, and it shows. In spite of that Mr Gates' frequent and eloquent tirades on the subject of PCs in the home, the plasma TV makers have not quite caught on. Fujitsus, or the Pioneer 5000EX are the only 'home styled' plasmas that work well with PCs. And they are display only models, no TV tuner.