Shawn,
Here is what little I know:
64 bit Windows will allow you to use more ram, and like Tyson said it is a little bit faster (but not a whole lot). Whether or not to go 64 bit is entirely up to you.
Cineform NeoScene is just the best .mts (AVCHD) to .avi converter available. It is $99.00 at https://www.videoguys.com. If you have a Q9650 coreduo quad, you don’t really need it, but it is nice to have, as it ‘relaxes’ the file compression quite a bit (i.e., makes the file larger), which means that the processor does not have to work nearly so hard to uncompress those teentsy-weentsy highly-compressed files in real time on the fly while editing. Since your processor has to work less, playback is less choppy: but my q9650 does the job even with stock .mts (avchd) files.
All you really need is these:
https://www.newegg.com/Product/Product.aspx?Item=N82E16819115130
https://www.newegg.com/Product/Product.aspx?Item=N82E16835100007
Also get coffee filters, and 95% pure rubbing alcohol (to clean off your heat sink or fan). Arctic Silver has instructions online as to how to install their product. Follow them closely. Or you can call a local computer tech to come do it for you for about $35.00 or something (and you can watch). Don’t use too much. It does not take much. Like maybe about a half inch worth of a toothpick. You just want to fill the tiny thin airgap between processor and the heat sink or fan heat sink.
64 bit windows is optional
more ram is optional
q9650 or above (core i7) is a must for AVCHD.
lots of guys use the 150. it is supposed to be excellent.
I convert to NeoScene .avi, but for a while I could not get it to work, and i used the native .mts files just fine.
Please let me know if I can be any more help.
Norman Willis
http://www.nazareneisrael.org
servant@nazareneisrael.org