Just what are the odds, anyway? Since mid-december I've managed to generate 200 BTC on a system that gives me about 45 Mhash/sec, only generating at nighttime and weekends. The first block was using just the 12 CPU cores, found it about two weeks into mining.

@ rebuilder The odds for my example can be crudely estimated at 1 in 1200 or so based on the 'average time' to find a block for that hashrate.  This is, of course, the same odds of that machine finding a block on any particular day, but we humans are psychologically biased towards early windfalls, so the earlier finds are more important to us .  In your case you could also get a crude estimate for that first block by taking the average time from http://www.alloscomp.com/bitcoin/calculator.php for your machine's cpu-only hashrate, and then adjusting for the proportion of days that you mine, with your final odds being (#of days you actually mined to find it) : (#of days you should have mined on average).  The overall take in the past month and a half is more complicated to estimate, but you're welcome to do that too if you want

@Mahkul odds around 1 in 404 Nice!!

Well, on rough estimates of my hash rate it seems over the course of 1.5 months I've found four blocks where on average one would be expected to find one.

Closest thing I even have to this would be gaining a share in slush's pool within 3 seconds of turning on the mining client.  For a 5-year old desktop with a CPU hash rate of 700 khash/s, this was actually a major accomplishment, hehe. 

Chances are very high I'll never find a block.  Even using the desktop, the laptop GPU, and both laptop CPU cores, my combined rate is still less than 5,000 khash/s.  Kinda a shame, but I didn't spend money on extra hardware so it's not like I have to make up the difference.

How's this for a beautiful fluke?  Block 866 found by Slush's mining pool was only the third share submitted for a round, 7 seconds after it began (average round time is 45 mins or so).  Those three people got a 16.6666 bitcoin bonus today in 7 seconds.  Not bad for pooled mining!

Yeah, I have a 5770 that I switch bag and forth between solo and pooled mining on whimsy.  In the last month I've earned 150 coins from pooled but nothing from solo despite hashing for much longer than the average time to find a block.  Just a couple rounds before the awesome round above I switched it back to solo.  D'OH!  True randomness is such a foreign concept to the human mind, though.  You practically have to physically restrain yourself from trying to find some sort of meaning in it.