IPIBL-LB from a quick Google search turns up with a G33 socket 775 motherboard.
Assuming this board has the same specs as the one on this site,
http://h10025.www1.hp.com/ewfrf/wc/document?cc=nz&lc=en&docname=c01324212
The best theoretical processor would be a Core 2 Quad Q9XXX series CPU, which is still quite high up in terms of computing power (a bit less than the first gen Core i5 (750), but still a very decent processor).
Graphic card wise, you can literally stick any modern (as in PCI-E) graphics card and it should work.
In terms of pricing, the problem here is that the LGA 775 platform is probably around 5 years old, that even the newer CPUs that have come out for it (C2Q Q9XXX) are no longer sold, or just expensive relative to other options.
For example the Core 2 Quad Q9550 on newegg costs $299.99, which is 70 dollars more expensive than the Core i5 2500K, a much newer and a faster processor.
That, and the fact that you literally have no upgrade options, would be my main concern for using this motherboard. DDR2 RAM that is used in this board cannot be used in future builds, for example.
I wouldn't know how much it would cost to make a build with an LGA 775 platform in 2012, but assuming you can get some cheap used CPUs (from a trusted seller, of course) off eBay could work (I'd still be a bit careful though, eBay being eBay). In terms of graphics, there really are no limitations as far as I'm concerned (you pay as much as you want for graphics, and I'm a bit rusty on current graphic card affairs)
The very best performance you could get is probably something like a Q9550 paired with the fastest GPU available, and
assuming that the Q9550 doesn't serve too much as a bottleneck to the latest graphic card, then you'd have a comparable build to high-range (graphics wise) today. CPU wise, it'd be average. The motherboard supports up to 8 GB of RAM, and that should be plenty for a gaming build.