|Most Acers have recovery partition - look on website (or supplied documentation) for how to use (often ALT+F10 keys when machine boots). If you use recovery option, you will lose all you data (again, sometime recovery option allows recovery into existing partition - which if available would allow you to access data, but not programs from current installation - there would need to be enough space on the C: drive to allow new installation. And as Acers often partition the hard drive into system & data, this may not be the case for you). You could also recover the data by booting from something like a Bartpe (google it) disk with an external hard drive attached.|
I have had much success with repair reinstall's on xp - but not unfortunately when the BSOD has a stop:c0000021a error.
If you can't access the recovery partition you will need an XP install disk to install from scratch.