I just bought an HD1500 via Newegg.com. It was a Rev B with 128MB RAM. It came with the 1.5 software, I had to upgrade first via CF. My impression from reading other posts here is that you have to upgrade the firmware via CF, other card types are supported. There are instructions in the Beta area. I used a 64MB CF card that I had handy.
FWIW...the Gallery Collection stuff that comes with the 1500 is on a 256MB CF card. For someone getting this model, in order to ugrade firmware, seems to me you should be able to put the formatup.roku on that card and do your update, but I didn't try that. All the GC stuff also comes with CD as's backup, so even if you hosed the content on the GC card using it to upgrade, you could easily restore it from the CD's.
I've had problems, but in general once upgraded to the .34 beta software and using MPlay for MPEG playback, I've been very happy with my Roku. I just need to go spend the $3500 or so to get the true HDTV I went, I watching so far in SVideo on a 36" CRT.
You most often find few praises for a product in support forums like this, but there ARE some here! Most people who post to forums like this are only doing so because they have a problem or want more features/capabilities from either the Roku itself or the 3rd party apps others have developed. That 3rd party capability is unique to the Roku vs. the other media streamers on the market, which was a big factor in why I chose it vs. the others.
HD-1500 RevB #1 (media room)
Mitsubishi WD-62528 62" LCD RPTV
Kenwood VR-407 receiver w/PSB Alpha's
PS/3 60GB (now 250GB) w/750GB Seagate ext
HD-1000 RevB #2 (bedroom)
Visco 32" LCD
AR 2.1 audio system