If potential cost savings are driving your desktop virtualization decision, beware the ROI killer: Over-provisioning.

Over-provisioning is a nice way of saying you're throwing money away. That could happen in a variety of forms, such as buying infrastructure that it better suited for a much larger company, planning for growth that doesn't happen, or not doing your homework on what other technology you'll need to support virtualization. But fear of wasteful spending shouldn't stop you in your virtual tracks; rather, it should motivate informed, careful decisions.

Raj Dhingra, CEO of NComputing, believes 2011 is a turning point in desktop virtualization deployments among small and midsize businesses. Dhingra, who left Citrix to take the NComputing helm in April, also said the broader field of virtualization vendors has taken note: "Everybody sees there is a big opportunity there."

As the number of viable virtual desktop infrastructure (VDI) options for SMBs increase, Dhingra recommends paying close attention to four key areas when making a decision. Doing so can help minimize the over-provisioning risk and ensure a real return on the investment.

1. Look for platforms specifically designed for SMBs. While a vendor's ability to scale with the growth of your company is important, don't let your daydreams overshadow your actual needs -- starting small can provide a bigger ROI in a shorter period time.

"Buy the shoe that fits rather than buying the shoe that's two sizes bigger in hopes that you're going to fit into it over time," Dhingra said.

The most obvious place to look is the cost per seat: This often tops the USD 1,000 mark in enterprise platforms, which makes the total cost of ownership (TCO) and return on investment (ROI) case trickier for SMBs. "If it's now costing you more than a PC, that's your first red flag," Dhingra said. He added that TCO/ROI analysis for a 100-seat deployment is not the same thing as a 100-seat proof of concept -- with an expectation that several thousand seats will be added later.

It should be noted that for some SMBs, ROI isn't just a matter of comparing virtual desktop versus traditional PC costs. At Infinity Sales Group, for example, both desktop support and power costs were major factors. For Silicon Valley Builders Group, mobility was the critical payoff in going virtual. In fact, the firm's CIO noted in an interview that just comparing per-seat costs can be a dead-end: "It would be a hard sell. Virtualization is still something like USD 1,200 per user, versus a PC I can go buy at Fry's for USD 500," he said.

No matter your particular business case, cost-per-seat is obviously still important. The moral: Don't pay for seats you don't need.

2. Know your supporting infrastructure needs. Desktop virtualization doesn't mean you're leaving hardware behind. Make sure you have a complete understanding of the supporting pieces you need, both on the server or host side and the client side. For the former, this includes things like servers, storage, and networking equipment. On the client side, don't forget to account for the actual devices -- such as thin clients, for example -- as well as your software needs.

Dhingra said not taking all the necessary components of VDI into account is a key budget pitfall for SMBs, particularly if the initial investment is based on an expectation of significant growth. It can also lead an organization to an infrastructure it's ill equipped to manage.

"That means not only the capital to actually procure [VDI], but then do I have internal expertise within my company to actually deal with this and work with it?" Dhingra said.

3. How many vendors are you willing to work with? Another possible sign you're headed down a path of over-provisioning: If your desktop virtualization project requires one or more multi-vendor components. This is likely a bigger issue for the "S" in SMB. While a midmarket firm with, say, 750 employees has more resources to manage multi-vendor platforms, a 50-person company might not want the potential headaches. More importantly, it might not have enough IT resources to do so. "It becomes a systems integration project that is typically suited to a larger company," Dhingra said.

4. How soon until you're up and running? You can't really start the ROI meter until your deployment is complete, right? For budget-constrained SMBs, a multi-month (or even year-plus) VDI project adds hidden costs --another form of over-provisioning -- that can immediately dull the shine of potential savings. Moreover, smaller companies usually thrive on their speed and agility -- IT projects should be no different. Dhingra said IT pros at SMBs should factor training and skills developments here, too: If you lose two days at an off-site training, for example, that's an expense -- even if the event is "free."