Actually you are going to see the prices begin to rise abit back up with the AMD offerings.
I see on ebay new OEM FX-60's can be bought for about $350.00 which is a super price when you consider they were over $1000.00 only 6 months ago.
I too have the same board as you along with Cas2 high performance memory, and I will be going with the FX-60 very soon. The FX-60 is very close in performance to the E6600, the challenge between those two chips is NO spanking for the the FX-60 by far.
Yes; the E6600 is faster but the FX-60 can still extend its arm and touch the back of the E6600! The unlocked multiplier on the FX-60 makes it an attractive alternative a complete system upgrade.
even more so if you have Cas 2 memory on the FX-60 platform, due to the cost of the PC8000 memory most people are opting for the more affordable DDR2533 & 6400 memory sticks. The DDR 6400 and under with its memory latencies are actually a lesser performer than the PC3200 memory.
Also Dont over look getting a 5000 X2
the diff in performance between the 5000 X2 and the E6600 is not worth the $800.00 to start fresh. Not when you can get a CPU that is very close in performance for $350.00 that should extend the life of your current investment by at least 18 months.
good luck & I hope you find a worthy CPu for your intended budget.