Perhaps I should explain further.
By support, I was referring to "driver support" in (pretty much) every modern OS out there. This is true of 3com, Intel, Realtek, and a few others. I've had bad experiences with Linksys products requiring kernel recompiles (*nix), pci slot adjustment, and needing to download a working driver (win2k). Sure, the "built-in" driver may not always be the best, but it is nice to have one so that you will be able to access the 'Net to download the most recent driver (if that is your thing). I recall purchasing a few linksys cards within the past couple months that came with driver disks lacking Windows 2000 drivers. It is comforting to freshly install your OS and know that you can access your network upon first boot. That is what I mean by support.
I actually do like the Realtek cards, such as the SMC you referred to. They are an excellent value, and like the 3com and Intel cards, are supported natively in _many_ OS's. The advantage to spending the extra few dollars for a 3com or Intel card comes mainly in performance. Now for most "home" users out there who are only concerned with getting online, this shouldn't matter too much. But when you are doing file transfers over a 100 Mbit LAN, you _will_ notice a difference between a Realtek and an Intel. The Intel will do it faster and use fewer CPU cycles.
I was able to puchase Intel cards for my entire network when Intel was having the 2* Pro100+ for $40 deal, but I would still gladly pay $50 for just one. It bothers me when people put together > $1000 systems and can't spend the extra $20-$30 to put a comparable network card in their system.
And finally, there is a reason why OEM's like Gateway exclusively use Intel cards in their computers. They have been proven to cause fewer problems than the so called "value" network cards out there.
~bex0rs