[BioC] Appropriate Probe annotation for HT-HGU133A chips

[Tipney, Hannah]

Please forgive this probably obvious question, but I am working with data from the High Throughput Affymetrix chips for the first time.
So simply, for the ht-hgu133a chips should I be using the hgu133a.db, hgu133a2.db or hgu133plus2.db Bioconductor probe annotations in conjunction with hthgu133acdf and hthgu133aprobe?
I assume hgu133a.db but it is not entirely clear from the Affymetrix site.
Thanks in advance
Hannah