IT Strategy for SME that scales and is cost effective

I don't have direct experience, but from colleagues the general rule of thumb seems to be that when small organisations outsource IT, there may be some financial savings, but there's also likely to be a drop in service (possibly just perceived, but more likely genuine).

The easy example I can give is of a school a friend worked at - they originally had 2 onsite IT support staff, but ended up outsourcing the service due to budget constraints. The problem is that now, not having people onsite and needing to route everything through the managed support service, faults take longer to resolve because there's nobody available onsite for the "I need this fixed right now or I can't teach this lesson" situations, so teachers end up reluctant to use the computing facilities in classrooms. They key here is poor identification of requirements when evaluating suppliers.

In terms of suggestions, there are a few things you should be considering:
1) Identify some way of automating software distribution to your machines. Desired State Configuration might be a good point to start - if need be, you could couple this with packaging up software installation packages into self-extracting executable files.
2) While your support is being provided internally, determine an accepted amount of time that is required to cover the minimum requirements (eg 1/4 of a full-time employee, etc) and figure out how this can be spread across existing staff. You may not be big enough to justify a dedicated full time person to fix it, but problems don't fix themselves and failing to have anyone who is responsible and empowered with keeping your productivity tools working just means everyone has to figure out how to fix stuff instead of doing the work they're paid to do.
3) Related to the previous point - use this as an opportunity to get some data on how often you need support and what sorts of support are required. This will help you draft requirements list with accurate details.
4) If you do go for the hardware-and-support-as-a-service option, make sure you get the terms of support absolutely nailed down - ie specific SLAs and response times (for email/chat, telephone, and on-site visits) specifed for requests, minor problems and major problems; get it in writing that the supplier covers all license and hardware costs; what happens in the event of SLA breach on their part; decide whether you require them to keep additional (suitably-patched-and-maintained) spare systems available in the event of hardware failure and if so how many spares should be kept, and so on.