AMD did deliver the killing blow to Sun. At least in the company I worked by then, they were all firmly Sun for the large compute servers until the Opteron arrived. PCs were nice as desktop machines, but large servers with multiple CPUs and lots of gigabytes of RAM were not feasible on x86 until the arrival of the Opterons. Eventually they would replace all Sparc based compute servers.
By the time the Opteron came out in 2003, Google was already a large company. My guess is they were already the largest search engine in the world -- and they ran their web crawler and search engine entirely on PCs.
Hotmail was bought by Microsoft in 1997, then Microsoft promptly announced that the service would be switched over to Windows. Till then, according to Wikipedia [1], Hotmail ran some Sun boxes, but also a lot of FreeBSD, and I am almost certain that the FreeBSD was running on PCs. They were probably the largest email provider in the world in 1997.
The Apache web server "was the most popular web server by Spring 1996 and stayed like that until the Summer of 2014" [2]. It ran and runs almost exclusively on Linux, which in turn ran and runs almost exclusively on x86.
Indeed, Intel got flat footed and was pushing for 64 bit only on itanium for a substantial price premium. AMD was first to market with the x86-64 instruction set and did quite well.
I wouldn't short-change AMD by saying their big success during that period was about the 32 vs 64 bit issue, or Itanium. They made the fastest 32-bit x86 chip in the world with the Athlon K7, and they did it four years before they launched their 64-bit chip.
Sure, but the opteron doubled down on it. They added x86-64 to a server class chip for the first time and they moved the memory controller on chip, which made the AMD scale dramatically better under a variety of workloads.
I believe a lot of people had the experience your company had at that time. But...
x86 (and Linux and Windows) started killing Unix and the other architectures a lot sooner than Opteron. At some point in the late nineties, SGI's workstation people pretty much curled up on the floor in the fetal position, moaning, "Windows NT, Windows NT." That spectacle was downright undignified, although the NT box they produced was impressive in its way. (They made some nice contributions to Linux nevertheless. Would that they had taken Linux even more seriously.) It says something about their outlook on the future of MIPS, as well as UNIX, that SGI designed their Visual Workstation using Pentium in an era when Windows NT on MIPS was still a thing.
You can't quite say that AMD64 killed sun. Sun actually made some decent, if overpriced, Opteron stuff. Sun's demise is a fun thing to discuss because former Sun employees often have an interesting opinion about where Sun went wrong. I'm waiting for the guy who says something like "yeah, that was my department's fault. We blew it and the company failed." So far I haven't seen that.
