I hadn't heard that there's going to be a new GPU lineup next month, but yes, Bulldozer (for what it means to people who hate buying Intel, but concede that they run the roost) will be "announced" next month. Yes, that announced is hypothetical. They've already changed the date twice before.
How much are you looking to spend? What resolution to you play on? What is your Power supply rated at?
Here's what Gigabyte listed for your Mobo:
2 x 1.5V DDR3 DIMM sockets supporting up to 4 GB of system memory
4 x 1.8V DDR2 DIMM sockets supporting up to 8 GB of system memory
Any SSD will fit your motherboard. It depends on if you have an open HDD bay to install one. Pick one in your budget, but with your Mobo, don't pay premium for SATA3. A SATA3 SSD will work on you board, but it will only be running at SATA2 speeds.
8800GTX is similar to the GTS250. This also puts it at 4850, 5750, 9800GTX+, etc territory. Not a bad card for gaming, but it uses more power. Grabbing a GTX460 or 6870 would be a good idea if your looking for more frames.
If you want to upgrade now, grab 2GBs of ram, a CPU cooler so you can OC your 9300 to above 3GHz, and one of those video cards. If you want to wait and see what BD brings then keep saving.