We have seen best performance numbers using Dell vostro 3460 laptop.
Coming to your second question, we would recommend you to go with 19.2 MHz crystal.
I experimented with 19.2MHz oscillator (ASDMB-19.200MHZ-LY) instead of crystal on FX3 DVK. See attached picture. Kit behavies with oscillator much better than with its default crystal. These are results of my noise test:
1) Oscillator, 3.3V GPIF , 1.5m USB cable, Renesas add-on adapter
01:39:36 Read/Write=200.8/106.7MB/s Errors PHY/LNK=0/0
2a) Crystal, 3.3V GPIF, same cable/adapter
00:00:01 Read/Write=194.2/104.5MB/s Errors PHY/LNK=14/0
Read from device failed (GetOverlappedResult error code=31)
A device attached to the system is not functioning.
2b) Crystal, 1.8V GPIF, same cable/adapter
00:01:47 Read/Write=201.9/103.3MB/s Errors PHY/LNK=96/1
FX3_DVK_OSC.jpg 76.6 K
Update to my previous post. It was actually 2m (and not 1.5m) USB cable I experimented with.
It's almost two years on, but thanks very much for your replies -- they were quite helpful!