It's not as simple as this. The servers we use are very high-end with 2 x quad-core processors, and each core hyper-threaded giving us "16 cores" per server in total. We also operate services which carefully manage the priority of every process to ensure that processes are spread most efficiently across all cores, and that each VPS gets a reasonable amount of CPU time. Having 200 processes running at once is almost nothing, the servers we use can can very easily handle significantly more processes than this with thousands of processes being quite normal without impacting performance at all.
Disk I/O isn't that much of a problem either to be honest, especially if using SAS disks in RAID10.
The above cannot be said about all VPS providers though.
What type of website/application do you need to host that requires such a high level of uptime/redundancy out of interest? It's good to see you are planning things properly.