Finally got my Gigabit switch installed - had a 24 port Netgear Prosafe (cheap from another forum), but the 2 fans on it were too noisy, so got a 16 Port Prosafe - much better
Got the following results:
Writing 1000 x 829440 byte frames into file \\Naslite-hdd\disk-1/framestream.dat
271 frames in 5.00 secs ==> 54.20 FPS (42.87 MB/s)
343 frames in 5.00 secs ==> 68.60 FPS (54.26 MB/s)
228 frames in 5.00 secs ==> 45.60 FPS (36.07 MB/s)
69 frames in 5.39 secs ==> 12.80 FPS (10.13 MB/s)
89 frames in 5.36 secs ==> 16.61 FPS (13.14 MB/s)
Write Summary : 1000.00 frames in 25.75 secs
: 12.80(min) 38.83(avg) 68.60(max) FPS
: 10.13(min) 30.72(avg) 54.26(max) MB/s
Reading 1000 x 829440 byte frames from file \\Naslite-hdd\disk-1/framestream.dat
252 frames in 5.00 secs ==> 50.40 FPS (39.87 MB/s)
254 frames in 5.00 secs ==> 50.80 FPS (40.18 MB/s)
259 frames in 5.02 secs ==> 51.64 FPS (40.85 MB/s)
235 frames in 4.67 secs ==> 50.30 FPS (39.79 MB/s)
Read Summary : 1000.00 frames in 19.69 secs
: 50.30(min) 50.79(avg) 51.64(max) FPS
: 39.79(min) 40.18(avg) 40.85(max) MB/s
Not earth shattering, but about four times faster than my previous results.