1. OEM software can be moved or resold. As discussed on another thread, these dodgy EULA terms can and have been challenged in court. Successfully. MS will always push the envelope if they think their illegal conduct will raise more $$ than the fine if they get caught. Chance of MS trying it on with big OEM license resale firms? Reasonable. Chance of them trying it on with private individuals? Pretty much zero.
2. If considering OpenOffice one might wish to research the Novell edition which has a number of enhancements, particularly in regard to MS Office compatibility. This includes full
VB macro support, and your pivot tables should work just fine. At one point Novell were offering near same-day turnaround with patches to address incompatibilities to enterprises evaluating OOo. It's just as free as the standard OOo, although they do also offer a paid version which contains a load of licensed truetype fonts for pretty much identical rendering to MS Office. 99% of Office users use less than 1% of the capability of Office 97, let alone the latest offerings. For the vast, vast majority OOo is perfectly adequate and will cost you nothing.