here's doGGy's post on turboing Martin's (malpaso) car:
http://www.6gc.net/forums/index.php?showtopic=44390&hl=that should be very helpful. I made my own list of parts I need to buy to turbo my 7A and got a lot of good stuff from that thread
here's my simplified list of things you would need...
turbo
log or B16 style manifold
custom downpipe
2 bar MAP sensor
fuel pump, 255lph
fuel pressure regulator
high impedence top feed injectors, 315cc or bigger
blow off valve
wastegate (if your turbo does not come with an internal)
boost controller
intercooler
piping, couplers, clamps to fit your setup
new clutch, at least stage 2
need to have your oil pan tapped and a fitting welded for the oil return line
cone air filter (if you still have the stock airbox)
piggyback fuel controller (SAFC)
exhaust system
various lines for oil and/or coolant to and from the turbo
gauge pod and guages if you want them
may want to relocate your oil filter
I haven't actually done it yet so there are probably more little stupid things you would need that aren't on the list, but those are the basics