France allies: Savoy, Westfalen, Bayern, Spain
Austria allies: Prussia (had to send troops, because of kingship-permission by the austrian emperor for prussian kingship), Württemberg, and of course UP and GB plus then also Portugal (allied with GB and UP ... UP was in reality directly under Wilhelm of Oranien, king of GB).
Genoa, Italy States and Venice - neutral ... while i would add military access for Austria, esp. on Venice ... the austrian Marshall Eugen of Savoyen attacked initially Milano etc. (the AI comicably always send this stack with the general Eugen of Savoyen to Venice border, but this stack does nothing all the time, we must try to change that passive behaviour).
Here is once more the link to wiki-Spanish-Successor-War:
http://en.wikipedia.org/wiki/War_of_the_Spanish_Succession ... the german article is better, more detailled, though.
Edit, short summary of the first war-years: Austria was in principle the initial actor in this war, which broke out into open violence in 1701. Austria sends troops to the river Rhein and Netherlands area, takes Köln and other german towns which sided France, formerly Eugen of Savoyen (austrian main general) attacks northern Italy ... GB general Churchill ("Marlborough") is very active on all fronts on the side of Austria with english-netherland troops. Else, many naval wars between english-netherland fleets and french-spanish fleets ... the english win mainly. On the iberian peninsula is then also war, english-netherland troops land on Portugal and together with them go into spanish lands ... during this war on the peninsula, Gibraltar will be taken, and later Barcelona, but nothing else special, mainland Spain stays spanish. In NA, the said conflicts evolve between GB and France, as for the lack of troops, mainly fought between Hurons (France) and Iroqouis (GB), known as "Queen Anne's War" (at this time, King Wilhelm died, and heir Anne is Queen).