I've had one fail - one in hundreds that I've used or sold or put into service. It died instantly and it was an Intel Engineering Sample (not for the retail or regular public). i5's and i7's are pretty decent CPUs. OP - do you know if you need cores or clock speed?
I like the i7-2600 for the bang for the buck. You can get it on the Dell XPS 8300 from their Outlet Site for as low as $739 which includes 12 Gigs of DDR SDRAM and a decent hard-drive, 16X DVD +/- RW Drive, and Windows 7 Home Premium. You can also find a unit with as much as 16 Gigs of RAM, and Windows Professional or Ultimate as well. You can also compare processors using the link at Passmark in terms of CPU Mark to Purchase Price: http://www.cpubenchmark.net/cpu_value_available.html Notice that the i7-2600 is at the TOP of the list, based on a $294 retail purchase price.
Multitasking will be rampant I assume this means the more cores the better right?I'm on the verge of buying AMD Six Core Fx-6100 3.3 Ghz on the ASUS M5a78l-m Lx motherboard
In general more core the better. However, the application must support it in order to use multiple cores. It is not a given. For example, TradeStation up to 9.0 does not support multi-core. When the overall CPU usage reaches 13%, charts start to freeze. Basically the "orchart.exe" process only works on 1 core, works it to death while the other 3 cores remain in idle. You should check with your trading software vendor.