I was going to say good luck with more than a couple of VPS's on that single HDD until @softsho011 beat me to it.
Short answer is NO - that server is not a good choice to offer VPS's on - there is insufficient Disk IO with a single HDD - and I would not put ANY clients on a machine with just a single drive, but it is OK to use as a personal dev/test machine for VM's.
At a minimum for offering VPS's, a pair of disks in Raid1, but then, you will still only be able to put a small number (probably 5-10 VM's). Really should be looking at RAID 10 as a minimum.
Now as a shared hosting server, I would still say NO - you should have raid1 as a minimum, and also a 3rd drive for your /backup While you might get away with it for the moment, it is certainly not ideal.
Finally, with the 1 IP you could get away with that for shared hosting, for VPS's you will require at least 1 IP per VPS.
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You definitely want to consider 4x HDD'S (Hardware RAID-10) so that you have room to place several containers on this machine and make a decent profit; disk I/O will be your bottle neck on a single or dual drive setup..