The best place to park for you lot will be the new official club carpark, which is behind the 'away end' (or at least behind the terrace where away fans tend to gather, at the oposite end of the ground from the Willows Clubhouse).
Think it's £3, it's supervised throughout the evening and is only a very short dash to the turnstiles, so you shouldn't get too wet (because it's hammering down here!)
The other alternatives are All Hallows school which is a couple of hundred yards up the road from the Willows or the Church car park which is on the opposite corner from the ground. Both are about the same price, are supervised but both are a little bit further away from where you'll need to get in.
As stated further up, there is plenty of on-road parking but obviously they're not supervised, and you'll need to be careful to ensure that you don't block driveways, etc.
The final option is Park and Ride. The Salford website
Come off the M602 at JuncÂtion 2, head towards Eccles (3rd exit off the roundÂabout) and take the first left at the next roundÂabout takÂing you past the West One retail comÂplex on the right. The free car park is next to the LadyÂwell MetÂrolink StaÂtion. The car park has CCTV and regÂuÂlar patrols and space for 400 cars. Take the MetÂrolink one stop up to the Weaste MetÂrolink staÂtion and then a short 250 yard walk up Weaste Road and Weaste Lane. If you show your MetÂrolink ticket when purÂchasÂing your match ticket at the ticket office on WilÂlows Road, we will refund the MetÂrolink ticket.[/i
The link above also provides directions and details for those visiting The Willows.
Hope that helps, see you there!