That chip will most likely overclock reasonably. Wtih a decent cooler, you're probably going to get it to about 3.5Ghz(if it were black edition), depending on the rest of your system. You may get a bit more than that, or you might get less.
The Athlon II are decent chips, hardware locked PII's, losing out on both cores and L3 cache. If you're lucky, you might be able to unlock it to a full quad core PII chip.
Problem is... the 245 isn't black edition, so you're limited to increasing the HT Ref. In this case, you'll need to lower the HT link speed, the CPU-NB speed, and the RAM speed in order to increase your CPU speed.
Try reducing your HT link and CPU-NB multiplier to 9, reduce your RAM by one speed slot (so 1066 to 800...) and set your HT ref to 225. Your board may be able to handle this, and it'll give you a CPU core speed of about 3.25GHz. Your RAM, if you set it to 800Mhz will be increased to 900, and your HT link and CPU-NB link will be at just over 2.0Ghz - where it was to begin with.
Try and get there slowly though, don't just bash it to that setting and go, as it may not work, and may cause issues.