From the anandtech article linked many times elsewhere: "Just in case you were told otherwise, the BTX form factor is largely incompatible with the ATX form factor..."
It looks from some of the pictures like the location of the slots will be entirely reversed, with the MoBo mounted on the other side of the case (Don't know if these pictures have been flipped however).
Luckily it looks like you'll still be able to use your existing PSU in most cases, unless you're trying to build a miniature sized system.
None of the articles I have seen even mention keeping an AGP port on the MoBo, but I suppose it could be possible for a manufacturer to put one in place of one of the PCI-X or PCI slots (with the correct spacing of course).
This is all assuming that you have good reason to bother upgrading such a system to BTX - why not keep it as ATX for now and then build your next one as BTX? After all, it is a shame to lose half of your components just to change the form factor, as you said...
My graphics card only has dvi-output, and come with a converter to vga. Admittedly it did cost a bomb (ATI AIW Radeon 9800Pro, 350 (Pounds Sterling)).
My monitor is fine with analogue input only - 17", 1600*1200@75Hz and with the sharpest focus I have ever seen on a monitor (except for a friend's 2700 workstation-grade laptop).
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From the anandtech article linked many times elsewhere: "Just in case you were told otherwise, the BTX form factor is largely incompatible with the ATX form factor..."
It looks from some of the pictures like the location of the slots will be entirely reversed, with the MoBo mounted on the other side of the case (Don't know if these pictures have been flipped however).
Luckily it looks like you'll still be able to use your existing PSU in most cases, unless you're trying to build a miniature sized system.
None of the articles I have seen even mention keeping an AGP port on the MoBo, but I suppose it could be possible for a manufacturer to put one in place of one of the PCI-X or PCI slots (with the correct spacing of course).
This is all assuming that you have good reason to bother upgrading such a system to BTX - why not keep it as ATX for now and then build your next one as BTX? After all, it is a shame to lose half of your components just to change the form factor, as you said...
My graphics card only has dvi-output, and come with a converter to vga. Admittedly it did cost a bomb (ATI AIW Radeon 9800Pro, 350 (Pounds Sterling)). My monitor is fine with analogue input only - 17", 1600*1200@75Hz and with the sharpest focus I have ever seen on a monitor (except for a friend's 2700 workstation-grade laptop).
Ummm, I hate to break it to you, but Mozilla (Firebird 0.7 on Win2k) seems to be vulnerable too - the test completely fooled my system...